Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2015
Accounting Policies [Abstract]
Basis of Presentation	The accompanying condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X promulgated by the Securities and Exchange Commission (the “SEC”). Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the six months ended June 30, 2015 are not necessarily indicative of the results that may be expected for the calendar year ending December 31, 2015. These unaudited financial statements should be read in conjunction with the audited financial statements and notes thereto included in our annual report on Form 10-K for the year ended December 31, 2014. The condensed consolidated financial statements include the accounts of ARMOUR Residential REIT, Inc. and its subsidiary. All intercompany accounts and transactions have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Significant estimates affecting the accompanying condensed consolidated financial statements include the valuation of Agency Securities (as defined below) and derivative instruments.
Cash	Cash Cash includes cash on deposit with financial institutions. We may maintain deposits in federally insured financial institutions in excess of federally insured limits. However, management believes we are not exposed to significant credit risk due to the financial position and creditworthiness of the depository institutions in which those deposits are held.
Cash Collateral Posted To/By Counterparties	Cash Collateral Posted To/By Counterparties Cash collateral posted to/by counterparties represents cash posted by us to counterparties or posted by counterparties to us as collateral for our interest rate swap contracts (including swaptions and basis swap contracts), Eurodollar Futures Contracts (“Futures Contracts”) and repurchase agreements on our Agency Securities and to-be-announced (“TBA”) Agency Securities.
Agency Securities, Available for Sale	Agency Securities, Available For Sale We generally intend to hold most of our Agency Securities for extended periods of time. We may, from time to time, sell any of our Agency Securities as part of the overall management of our securities portfolio. Management determines the appropriate classifications of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. At June 30, 2015 and December 31, 2014, all of our Agency Securities were classified as available for sale securities. Agency Securities classified as available for sale are reported at their estimated fair values with unrealized gains and losses excluded from earnings and reported as part of the condensed consolidated statements of comprehensive income (loss).
Receivables and Payable for Unsettled Sales and Purchases	Receivables and Payables for Unsettled Sales and Purchases We account for purchases and sales of securities on the trade date, including purchases and sales for forward settlement. Receivables and payables for unsettled trades represent the agreed trade price multiplied by the outstanding balance of the securities at the balance sheet date.
Accrued Interest Receivable and Payable	Accrued Interest Receivable and Payable Accrued interest receivable includes interest accrued between payment dates on Agency Securities. Accrued interest payable includes interest payable on our repurchase agreements and may, at certain times, contain interest payable on U.S. Treasury Securities sold short.
Repurchase Agreements and Obligations to Return Securities Received as Collateral, at Fair Value	Obligations to Return Securities Received as Collateral, at Fair Value At certain times, we also sell to third parties the U.S. Treasury Securities received as collateral for reverse repurchase agreements and recognize the resulting obligation to return said U.S. Treasury Securities as a liability on our condensed consolidated balance sheets. Interest is recorded on the repurchase agreements, reverse repurchase agreements and U.S. Treasury Securities sold short on an accrual basis and presented as interest expense. Both parties to the transaction have the right to make daily margin calls based on changes in the fair value of the collateral received and/or pledged. Repurchase Agreements We finance the acquisition of our Agency Securities through the use of repurchase agreements. Our repurchase agreements are secured by our Agency Securities and bear interest rates that have historically moved in close relationship to the Federal Funds Rate and the London Interbank Offered Rate (“LIBOR”). Under these repurchase agreements, we sell Agency Securities to a lender and agree to repurchase the same Agency Securities in the future for a price that is higher than the original sales price. The difference between the sales price that we receive and the repurchase price that we pay represents interest paid to the lender. A repurchase agreement operates as a financing arrangement under which we pledge our Agency Securities as collateral to secure a loan which is equal in value to a specified percentage of the estimated fair value of the pledged collateral. We retain beneficial ownership of the pledged collateral. At the maturity of a repurchase agreement, we are required to repay the loan and concurrently receive back our pledged collateral from the lender or, with the consent of the lender, we may renew such agreement at the then prevailing interest rate. The repurchase agreements may require us to pledge additional assets to the lender in the event the estimated fair value of the existing pledged collateral declines. In addition to the repurchase agreement financing discussed above, at certain times we have entered into reverse repurchase agreements with certain of our repurchase agreement counterparties. Under a typical reverse repurchase agreement, we purchase U.S. Treasury Securities from a borrower in exchange for cash and agree to sell the same securities in the future in exchange for a price that is higher than the original purchase price. The difference between the purchase price originally paid and the sale price represents interest received from the borrower. Reverse repurchase agreement receivables and repurchase agreement liabilities are presented net when they meet certain criteria, including being with the same counterparty, being governed by the same master repurchase agreement ("MRA"), settlement through the same brokerage or clearing account and maturing on the same day.
Derivatives, at Fair Value	Derivatives, at Fair Value We recognize all derivatives as either assets or liabilities at fair value on our condensed consolidated balance sheets. All changes in the fair values of our derivatives are reflected in our condensed consolidated statements of operations. We designate derivatives as hedges for tax purposes and any unrealized derivative gains or losses would not affect our distributable net taxable income. These transactions include interest rate swap contracts, interest rate swaptions and basis swap contracts. We also utilize forward contracts for the purchase or sale of TBA Agency Securities. We account for TBA Agency Securities as derivative instruments if it is reasonably possible that we will not take or make physical delivery of the Agency Security upon settlement of the contract. We may also enter into TBA Agency Securities as a means of investing in and financing Agency Securities (thereby increasing our "at risk" leverage) or as a means of disposing of or reducing our exposure to Agency Securities (thereby reducing our "at risk" leverage). Pursuant to TBA Agency Securities, we agree to purchase or sell, for future delivery, Agency Securities with certain principal and interest terms and certain types of collateral, but the particular Agency Securities to be delivered are not identified until shortly before the TBA settlement date. We may also choose, prior to settlement, to move the settlement of these securities out to a later date by entering into an offsetting short or long position (referred to as a "pair off"), net settling the paired off positions for cash, and simultaneously purchasing or selling a similar TBA Agency Security for a later settlement date. This transaction is commonly referred to as a "dollar roll." When it is reasonably possible that we will pair off a TBA Agency Security, we account for that contract as a derivative.
Preferred Stock and Common Stock	Preferred Stock At June 30, 2015, we were authorized to issue up to 50,000 shares of preferred stock, par value $0.001 per share, with such designations, voting and other rights and preferences as may be determined from time to time by our Board of Directors (“Board”) or a committee thereof. We have designated 9,610 shares as 8.250% Series A Preferred Stock and 6,210 shares as 7.875% Series B Preferred Stock. At June 30, 2015, a total of 34,180 shares of our authorized preferred stock remain available for designation as future series. Series A Preferred Stock At June 30, 2015 and December 31, 2014, we had 2,181 shares of Series A Preferred Stock issued and outstanding with a par value of $0.001 per share and a liquidation preference of $25.00 per share, or $54,514 in the aggregate. At June 30, 2015 and December 31, 2014, there were no accrued or unpaid dividends on the Series A Preferred Stock. The Series A Preferred Stock is entitled to a dividend at a rate of 8.250% per year based on the $25.00 per share liquidation preference before the common stock is entitled to receive any dividends. The Series A Preferred Stock is redeemable at $25.00 per share plus accrued and unpaid dividends exclusively at our option commencing on June 7, 2017 (subject to our right under limited circumstances to redeem the Series A Preferred Stock earlier in order to preserve our qualification as a REIT). The Series A Preferred Stock is senior to our common stock and therefore in the event of liquidation, dissolution or winding up, the Series A Preferred Stock will receive a liquidation preference of $25.00 per share plus accumulated and unpaid dividends before distributions are paid to holders of our common stock, with no right or claim to any of our remaining assets thereafter. The Series A Preferred Stock generally does not have voting rights, except if we fail to pay dividends on the Series A Preferred Stock for eighteen months, whether or not consecutive. Under such circumstances, the Series A Preferred Stock will be entitled to vote to elect two additional directors to the Board, until all unpaid dividends have been paid or declared and set aside for payment. The Series A Preferred Stock has no stated maturity, is not subject to any sinking fund or mandatory redemption and will remain outstanding indefinitely unless repurchased or redeemed by us or converted into our common stock in connection with a change of control by the holders of Series A Preferred Stock. Series B Preferred Stock At June 30, 2015 and December 31, 2014, we had 5,650 shares of Series B Preferred Stock issued and outstanding with a par value of $0.001 per share and a liquidation preference of $25.00 per share, or $141,250 in the aggregate. At June 30, 2015 and December 31, 2014, there were no accrued or unpaid dividends on the Series B Preferred Stock. The Series B Preferred Stock is entitled to a dividend at a rate of 7.875% per year based on the $25.00 per share liquidation preference before the common stock is entitled to receive any dividends. The Series B Preferred Stock is redeemable at $25.00 per share plus accrued and unpaid dividends exclusively at our option commencing on February 12, 2018 (subject to our right under limited circumstances to redeem the Series A Preferred Stock earlier in order to preserve our qualification as a REIT). The Series B Preferred Stock is senior to our common stock and ranks on parity with the Series A Preferred Stock. In the event of liquidation, dissolution or winding up, the Series B Preferred Stock will receive a liquidation preference of $25.00 per share plus accumulated and unpaid dividends before distributions are paid to holders of our common stock, with no right or claim to any of our remaining assets thereafter. The Series B Preferred Stock generally does not have voting rights, except if we fail to pay dividends on the Series B Preferred Stock for eighteen months, whether or not consecutive. Under such circumstances, the Series B Preferred Stock will be entitled to vote to elect two additional directors to the Board, until all unpaid dividends have been paid or declared and set aside for payment. The Series B Preferred Stock has no stated maturity, is not subject to any sinking fund or mandatory redemption and will remain outstanding indefinitely unless repurchased or redeemed by us or converted into our common stock in connection with a change of control by the holders of Series B Preferred Stock. Common Stock Common Stock At June 30, 2015, we were authorized to issue up to 1,000,000 shares of common stock, par value $0.001 per share, with such designations, voting and other rights and preferences as may be determined from time to time by our Board. We had 350,271 shares of common stock issued and outstanding at June 30, 2015 and 353,159 shares of common stock issued and outstanding at December 31, 2014. Common Stock Repurchased On March 5, 2014, our Board increased the authorization under our Repurchase Program to 50,000 shares of our common stock outstanding. Under the Repurchase Program, shares may be purchased in the open market, including block trades, through privately negotiated transactions, or pursuant to a trading plan separately adopted in the future. The timing, manner, price and amount of any repurchases will be at our discretion, subject to the requirements of the Securities Exchange Act of 1934, as amended, and related rules. We are not required to repurchase any shares under the Repurchase Program and it may be modified, suspended or terminated at any time for any reason. We do not intend to purchase shares from our Board or other affiliates. Under Maryland law, such repurchased shares are treated as authorized but unissued. For the six months ended June 30, 2015, we repurchased 3,075 shares of our common stock under the Repurchase Program for an aggregate of $9,497.
Revenue Recognition	Revenue Recognition Interest income is earned and recognized on Agency Securities based on their unpaid principal amounts and their contractual terms. Recognition of interest income commences on the settlement date of the purchase transaction and continues through the settlement date of the sale transaction. Premiums and discounts associated with the purchase of Multi-Family mortgage backed securities (“MBS”), which are generally not subject to prepayment, are amortized or accreted into interest income over the contractual lives of the securities using a level yield method. Premiums and discounts associated with the purchase of other Agency Securities are amortized or accreted into interest income over the actual lives of the securities, reflecting actual prepayments as they occur.
Fair Value of Agency Securities	Fair Value of Agency Securities: We invest in Agency Securities representing interests in or obligations backed by pools of fixed rate, hybrid adjustable rate and adjustable rate mortgage loans. The authoritative literature requires us to classify our investments as either trading, available for sale or held to maturity securities. Management determines the appropriate classifications of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. We currently classify all of our Agency Securities as available for sale. Agency Securities classified as available for sale are reported at their estimated fair values with unrealized gains and losses excluded from earnings and reported as part of the statements of comprehensive income (loss). Security purchase and sale transactions, including purchase of TBA Agency Securities, are recorded on the trade date to the extent it is probable that we will take or make timely physical delivery of the related securities. Gains or losses realized from the sale of securities are included in income and are determined using the specific identification method.
Impairment of Assets	Impairment of Assets: We evaluate Agency Securities for other than temporary impairment at least on a quarterly basis and more frequently when economic or market concerns warrant such evaluation. We consider an impairment to be other than temporary if we (1) have the intent to sell the Agency Securities, (2) believe it is more likely than not that we will be required to sell the securities before recovery (for example, because of liquidity requirements or contractual obligations) or (3) a credit loss exists. Impairment losses recognized establish a new cost basis for the related Agency Securities.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) refers to changes in equity during a period from transactions and other events and circumstances from non-owner sources. It includes all changes in equity during a period, except those resulting from investments by owners and distributions to owners.
New Accounting Pronouncements	In June 2014, the Financial Accounting Standards Board issued ASU 2014-11, Repurchase-to Maturity Transactions, Repurchase Financing, and Disclosures, Transfers and Servicing (Topic 860). We do not have repurchase-to-maturity transactions or repurchase financing arrangements of the type covered by ASU 2014-11, therefore this amendment to the accounting standards will not affect our condensed consolidated balance sheets or statements of operations. The amendment also requires certain additional disclosures about repurchase agreements beginning with these second quarter 2015 financial statements, See Note 7, “Repurchase Agreements”.