| Pay vs Performance Disclosure | 12 Months Ended |
| Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) |
| Pay vs Performance Disclosure [Table] | | | |
| Pay vs Performance [Table Text Block] | Value of Initial Fixed $100 Investment Based on: Year Summary Compensation Table Total for Each Co-PEO (1) Compensation Actually paid to Each Co-PEO (2) Average Summary Compensation Table Total for Non-PEO NEOs (3) Average Compensation Actually Paid to Non-PEO NEOs (2) Total Shareholder Return (4) Peer Group Total Shareholder Return (5) Net Income (Loss) Total Economic Return (6) 2022 $ — $ (750,654) $ — $ (142,055) $ 46.06 $ 77.24 $ (229,930) (32.4) % 2021 $ 1,986,090 $ 1,823,636 $ 184,667 $ 170,850 $ 67.53 $ 97.01 $ 15,363 (6.4) % 2020 $ 1,933,320 $ 92,429 $ 693,702 $ (93,459) $ 66.74 $ 95.01 $ (215,112) (35.1) % | | |
| Company Selected Measure Name | Total Economic Return | | |
| Named Executive Officers, Footnote [Text Block] | In all the years in question, Scott J. Ulm and Jeffrey J. Zimmer served as the Company's Co-Chief Executive Officers and received identical compensation.In all the years in question, the Non-PEO NEOs consisted of James R. Mountain, Mark R. Gruber and Gordon M. Harper. | | |
| Peer Group Issuers, Footnote [Text Block] | Total Shareholder Return illustrates the value, as of the last day of the indicated fiscal year, of an investment of $100 in the peer group on December 31, 2019. See the subsection above titled, "ARMOUR’s Mortgage REIT Peer Group" for a description of the peer group used in this calculation. | | |
| Adjustment To PEO Compensation, Footnote [Text Block] | The following tables set forth the amounts subtracted from the Summary Compensation Table Total and the amounts added back during each year represented in the Pay versus Performance table to arrive at Compensation Actually Paid to each of our Co-PEOs and our Non PEO NEOs during the years presented. Equity values are calculated in accordance with ASC Topic 718. Adjustments made to Determine Compensation Actually Paid 2022 2021 2020 Deduction for amounts reported under the “Stock Awards” column in the Summary Compensation Table Each Co-PEO $ — $ (1,986,090) $ (1,933,320) Average Non PEO NEOs $ — $ (184,667) $ (693,702) Increase for year-end fair value of awards granted during year that remain unvested as of year-end Each Co-PEO $ — $ 1,487,687 $ 909,813 Average Non PEO NEOs $ — $ 137,340 $ 374,629 Deduction for change in fair value from prior year-end to current year-end of awards granted prior to that year that were outstanding and unvested as of year-end Each Co-PEO $ (685,729) $ (233,446) $ (942,490) Average Non PEO NEOs $ (108,680) $ (43,407) $ (324,642) Increase for fair value as of the vesting dates for awards granted during year that vest during the year Each Co-PEO $ — $ 308,016 $ 262,811 Average Non PEO NEOs $ — $ 29,760 $ 101,706 Deduction for change in fair value from prior year-end to current year-end of awards granted prior to that year that vested during year Each Co-PEO $ (309,989) $ (72,677) $ (326,246) Average Non PEO NEOs $ (76,466) $ (17,862) $ (107,474) Deduction for fair value of awards granted prior to year that were forfeited during year Each Co-PEO $ — $ — $ — Average Non PEO NEOs $ — $ — $ (202,527) Increase based on dividends or other earnings Paid during year prior to vesting date of award Each Co-PEO $ 245,064 $ 334,056 $ 188,541 Average Non PEO NEOs $ 43,091 $ 65,019 $ 64,849 Totals Each Co-PEO $ (750,654) $ (162,454) $ (1,840,891) Average Non PEO NEOs $ (142,055) $ (13,817) $ (787,161) | | |
| Non-PEO NEO Average Total Compensation Amount | $ 0 | $ 184,667 | $ 693,702 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ (142,055) | 170,850 | (93,459) |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | The following tables set forth the amounts subtracted from the Summary Compensation Table Total and the amounts added back during each year represented in the Pay versus Performance table to arrive at Compensation Actually Paid to each of our Co-PEOs and our Non PEO NEOs during the years presented. Equity values are calculated in accordance with ASC Topic 718. Adjustments made to Determine Compensation Actually Paid 2022 2021 2020 Deduction for amounts reported under the “Stock Awards” column in the Summary Compensation Table Each Co-PEO $ — $ (1,986,090) $ (1,933,320) Average Non PEO NEOs $ — $ (184,667) $ (693,702) Increase for year-end fair value of awards granted during year that remain unvested as of year-end Each Co-PEO $ — $ 1,487,687 $ 909,813 Average Non PEO NEOs $ — $ 137,340 $ 374,629 Deduction for change in fair value from prior year-end to current year-end of awards granted prior to that year that were outstanding and unvested as of year-end Each Co-PEO $ (685,729) $ (233,446) $ (942,490) Average Non PEO NEOs $ (108,680) $ (43,407) $ (324,642) Increase for fair value as of the vesting dates for awards granted during year that vest during the year Each Co-PEO $ — $ 308,016 $ 262,811 Average Non PEO NEOs $ — $ 29,760 $ 101,706 Deduction for change in fair value from prior year-end to current year-end of awards granted prior to that year that vested during year Each Co-PEO $ (309,989) $ (72,677) $ (326,246) Average Non PEO NEOs $ (76,466) $ (17,862) $ (107,474) Deduction for fair value of awards granted prior to year that were forfeited during year Each Co-PEO $ — $ — $ — Average Non PEO NEOs $ — $ — $ (202,527) Increase based on dividends or other earnings Paid during year prior to vesting date of award Each Co-PEO $ 245,064 $ 334,056 $ 188,541 Average Non PEO NEOs $ 43,091 $ 65,019 $ 64,849 Totals Each Co-PEO $ (750,654) $ (162,454) $ (1,840,891) Average Non PEO NEOs $ (142,055) $ (13,817) $ (787,161) | | |
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | | | |
| Compensation Actually Paid vs. Net Income [Text Block] | | | |
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | | | |
| Tabular List [Table Text Block] | The following is a list of the most important factors used by the Company to link executive compensation actually paid to the Co-PEOs and Non-PEO NEOs. (1) Economic return. (2) Total shareholder return. (3) Common equity growth through efficient use of the Company's at-the-market common stock offering program. (4) Equity growth in percentage terms as compared to the peer group. (5) CEO open market purchases of Company common stock as compared to open market purchases of common stock by peer group CEOs. (6) Strategic implementation and sale of a preferred stock program as compared to the Company's peer group. | | |
| Total Shareholder Return Amount | $ 46.06 | 67.53 | 66.74 |
| Peer Group Total Shareholder Return Amount | 77.24 | 97.01 | 95.01 |
| Net Income (Loss) | $ (229,930,000) | $ 15,363,000 | $ (215,112,000) |
| Company Selected Measure Amount | (0.324) | (0.064) | (0.351) |
| Additional 402(v) Disclosure [Text Block] | Total Shareholder Return illustrates the value, as of the last day of the indicated fiscal year, of an investment of $100 in our common stock on December 31, 2019. See graphs below for the relationship between Total Shareholder Return and other metrics in this table. | | |
| Measure [Axis]: 1 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Economic return | | |
| Non-GAAP Measure Description [Text Block] | Total Economic Return is calculated by adding the year-end book value per common share for the particular year plus dividends paid per common share for such year and then dividing the sum by book value per common share at the beginning of the year. Book value per common share is calculated as total stockholders' equity, less the liquidation preference on shares of our outstanding Series C Preferred Stock of $171,174,450, divided by common shares outstanding. | | |
| Measure [Axis]: 2 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Total shareholder return | | |
| Measure [Axis]: 3 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Common equity growth through efficient use of the Company's at-the-market common stock offering program | | |
| Measure [Axis]: 4 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Equity growth in percentage terms as compared to the peer group | | |
| Measure [Axis]: 5 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | CEO open market purchases of Company common stock as compared to open market purchases of common stock by peer group CEOs | | |
| Measure [Axis]: 6 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Strategic implementation and sale of a preferred stock program as compared to the Company's peer group | | |
| Ulm [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| PEO Total Compensation Amount | $ 0 | $ 1,986,090 | $ 1,933,320 |
| PEO Actually Paid Compensation Amount | $ (750,654) | 1,823,636 | 92,429 |
| PEO Name | Scott J. Ulm | | |
| Zimmer [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| PEO Total Compensation Amount | $ 0 | 1,986,090 | 1,933,320 |
| PEO Actually Paid Compensation Amount | $ (750,654) | 1,823,636 | 92,429 |
| PEO Name | Jeffrey J. Zimmer | | |
| PEO [Member] | Ulm [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ (750,654) | (162,454) | (1,840,891) |
| PEO [Member] | Ulm [Member] | Stock Awards Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | (1,986,090) | (1,933,320) |
| PEO [Member] | Ulm [Member] | Equity Awards Granted During the Year, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 1,487,687 | 909,813 |
| PEO [Member] | Ulm [Member] | Equity Awards Granted During the Year, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (685,729) | (233,446) | (942,490) |
| PEO [Member] | Ulm [Member] | Equity Awards Granted In Prior Years, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 308,016 | 262,811 |
| PEO [Member] | Ulm [Member] | Equity Awards Granted In Prior Years, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (309,989) | (72,677) | (326,246) |
| PEO [Member] | Ulm [Member] | Equity Awards That Forfeited During The Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| PEO [Member] | Ulm [Member] | Value Of Dividends Or Other Earnings Paid Adjustment [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 245,064 | 334,056 | 188,541 |
| PEO [Member] | Zimmer [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (750,654) | (162,454) | (1,840,891) |
| PEO [Member] | Zimmer [Member] | Stock Awards Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | (1,986,090) | (1,933,320) |
| PEO [Member] | Zimmer [Member] | Equity Awards Granted During the Year, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 1,487,687 | 909,813 |
| PEO [Member] | Zimmer [Member] | Equity Awards Granted During the Year, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (685,729) | (233,446) | (942,490) |
| PEO [Member] | Zimmer [Member] | Equity Awards Granted In Prior Years, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 308,016 | 262,811 |
| PEO [Member] | Zimmer [Member] | Equity Awards Granted In Prior Years, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (309,989) | (72,677) | (326,246) |
| PEO [Member] | Zimmer [Member] | Equity Awards That Forfeited During The Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| PEO [Member] | Zimmer [Member] | Value Of Dividends Or Other Earnings Paid Adjustment [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 245,064 | 334,056 | 188,541 |
| Non-PEO NEO [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (142,055) | (13,817) | (787,161) |
| Non-PEO NEO [Member] | Stock Awards Adjustments [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | (184,667) | (693,702) |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 137,340 | 374,629 |
| Non-PEO NEO [Member] | Equity Awards Granted During the Year, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (108,680) | (43,407) | (324,642) |
| Non-PEO NEO [Member] | Equity Awards Granted In Prior Years, Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 29,760 | 101,706 |
| Non-PEO NEO [Member] | Equity Awards Granted In Prior Years, Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (76,466) | (17,862) | (107,474) |
| Non-PEO NEO [Member] | Equity Awards That Forfeited During The Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | (202,527) |
| Non-PEO NEO [Member] | Value Of Dividends Or Other Earnings Paid Adjustment [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ 43,091 | $ 65,019 | $ 64,849 |
