XML 96 R85.htm IDEA: XBRL DOCUMENT
v3.20.2

Stockholders' Equity (Narrative) (Details) |  |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended | 202 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Aug. 12, 2020 $ / shares | Aug. 06, 2020 $ / shares | Jul. 01, 2020 $ / shares | Jun. 15, 2020 USD ($) $ / shares shares | Mar. 02, 2020 USD ($) | Feb. 28, 2020 $ / shares shares | Feb. 14, 2020 $ / shares | Apr. 15, 2013 $ / shares shares | Mar. 31, 2020 quarter director | Sep. 30, 2020 USD ($) $ / shares shares | Sep. 30, 2019 $ / shares | Jun. 30, 2019 $ / shares | Mar. 31, 2019 $ / shares | Sep. 30, 2020 USD ($) quarter director $ / shares shares | Sep. 30, 2019 USD ($) | Dec. 31, 2019 $ / shares shares | Jun. 30, 2020 USD ($) shares | Oct. 15, 2019 shares | Aug. 16, 2019 USD ($) | Dec. 31, 2013 shares | Aug. 31, 2005 shares
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, cash dividends declared (in dollars per share) |  | $ 0.05 |  |  |  |  |  |  |  | $ 0.05 | $ 0.20 | $ 0.20 | $ 0.20 |  |  |  |  |  |  |  |
Proceeds from issuance of redeemable preferred stock | $ |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 275,000,000 | $ 0 |  |  |  |  |  |
Aggregate number of shares of common stock authorized (in shares) | shares |  |  |  |  |  |  |  |  |  | 874,300,000 |  |  |  | 874,300,000 |  | 886,950,000 |  |  |  |  |
Number of shares authorized to be repurchased under the Repurchase Program (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000.0 | 4,000,000.0
Number of remaining shares authorized to be repurchased under the Repurchase Program (in shares) | shares |  |  |  |  |  |  |  |  |  | 6,616,355 |  |  |  | 6,616,355 |  |  |  |  |  |  |
Number of shares called by warrant (in shares) | shares |  |  |  | 37,039,106 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of warrants | $ |  |  |  | $ 495,000,000.0 |  |  |  |  |  |  |  |  |  | $ 14,041,000 | $ 0 |  |  |  |  |  |
DRSPP |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate number of shares of common stock authorized (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9,000,000.0 |  |  |
Shares of common stock authorized and available for issuance (in shares) | shares |  |  |  |  |  |  |  |  |  | 8,800,000 |  |  |  | 8,800,000 |  |  |  |  |  |  |
Common shares issued through DRSPP (in shares) | shares |  |  |  |  |  |  |  |  |  | 4,374 |  |  |  | 137,740 |  |  | 34,516,508 |  |  |  |
Net proceeds from shares issued through DRSPP | $ |  |  |  |  |  |  |  |  |  | $ 11,688 |  |  |  | $ 752,095 |  |  | $ 287,300,000 |  |  |  |
Series B Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred Stock, dividend rate |  |  |  |  |  |  |  |  |  |  |  |  |  | 7.50% |  | 7.50% |  |  |  |  |
Preferred stock, shares issued (in shares) | shares |  |  |  |  |  |  |  |  |  | 8,000,000 |  |  |  | 8,000,000 |  | 8,000,000 |  |  |  |  |
Preferred stock par value (usd per share) |  |  |  |  |  |  |  |  |  | $ 0.01 |  |  |  | $ 0.01 |  | $ 0.01 |  |  |  |  |
Dividend declared per share, preferred stock (in dollars per share) | $ 0.46875 |  | $ 0.9375 |  |  |  | $ 0.46875 |  |  | $ 1.40625 | $ 0.46875 | $ 0.46875 | $ 0.46875 |  |  |  |  |  |  |  |
Series C Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred Stock, dividend rate |  |  |  |  |  |  |  |  |  |  |  |  |  | 6.50% |  |  |  |  |  |  |
Preferred stock, shares issued (in shares) | shares |  |  |  |  |  |  |  |  |  | 11,000,000 |  |  |  | 11,000,000 |  |  |  |  |  |  |
Preferred stock par value (usd per share) |  |  |  |  |  |  |  |  |  | $ 0.01 |  |  |  | $ 0.01 |  |  |  |  |  |  |
Dividend declared per share, preferred stock (in dollars per share) |  |  |  |  |  |  |  |  |  | 0.93889 |  |  |  |  |  |  |  |  |  |  |
Amount of preferred dividends in arrears (USD per share) | $ 0.40625 |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.53264 |  |  |  |  |  |  |
Preferred Stock | Series B Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred Stock, dividend rate |  |  |  |  |  |  |  | 7.50% |  |  |  |  |  | 7.50% | 7.50% |  |  |  |  |  |
Preferred stock, shares issued (in shares) | shares |  |  |  |  |  |  |  | 8,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock par value (usd per share) |  |  |  |  |  |  |  | $ 0.01 |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, liquidation preference (in dollars per share) |  |  |  |  |  |  |  | 25.00 |  | $ 25.00 |  |  |  | $ 25.00 |  | $ 25.00 |  |  |  |  |
Preferred stock, redemption price (in dollars per share) |  |  |  |  |  |  |  | $ 25.00 |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum quarters without dividends to get voting rights, in quarters | quarter |  |  |  |  |  |  |  |  |  |  |  |  |  | 6 |  |  |  |  |  |  |
Number of additional directors that can be elected by preferred stock holders | director |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |
Percentage required for making material changes |  |  |  |  |  |  |  | 66.67% |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred Stock | Series C Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred Stock, dividend rate |  |  |  |  |  | 6.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares issued (in shares) | shares |  |  |  |  |  | 11,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock par value (usd per share) |  |  |  |  |  | $ 0.01 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, liquidation preference (in dollars per share) |  |  |  |  |  | 25.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, redemption price (in dollars per share) |  |  |  |  |  | $ 25.00 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum quarters without dividends to get voting rights, in quarters | quarter |  |  |  |  |  |  |  |  | 6 |  |  |  |  |  |  |  |  |  |  |  |
Number of additional directors that can be elected by preferred stock holders | director |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |  |  |
Shares reclassified to redeemable capital stock (in shares) | shares |  |  |  |  |  | 12,650,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of redeemable preferred stock | $ |  |  |  |  | $ 266,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of warrants | $ |  |  |  | $ 14,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
At The Market |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
At-the-market, maximum potential proceeds | $ |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 400,000,000.0 |  |
Sales commission of gross sales price |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2.00% |  |
Number of shares issued (in shares) | shares |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |
Value remaining outstanding for future offerings | $ |  |  |  |  |  |  |  |  |  | $ 390,000,000.0 |  |  |  | $ 390,000,000.0 |  |  |  |  |  |  |
LIBOR | Preferred Stock | Series C Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, basis spread on variable rate |  |  |  |  |  | 5.345% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercise Price Range One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrant exercise price (usd per share) |  |  |  | $ 1.66 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exercise Price Range Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrant exercise price (usd per share) |  |  |  | $ 2.08 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stockholders' Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of warrants | $ |  |  |  | $ 481,000,000.0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

X
- Definition At The Market, Potential Proceeds + References No definition available. + Details
Name: | mfa_AtTheMarketPotentialProceeds
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Maximum Times Series B Receives No Dividends in Order for Voting Rights + References No definition available. + Details
Name: | mfa_MaximumTimesSeriesBReceivesNoDividendsinOrderforVotingRights
Namespace Prefix: | mfa_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of additional directors that can be elected by the preferred stock holders on getting the voting rights. + References No definition available. + Details
Name: | mfa_PreferredStockVotingRightsNumberOfAdditionalDirectorsThatCanBeElected
Namespace Prefix: | mfa_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The minimum percentage of preferred stock holders' affirmative vote necessary to make certain material and adverse changes to the terms of the preferred stock. + References No definition available. + Details
Name: | mfa_PreferredStockVotingRightsPercentageRequiredForMakingMaterialAndAdverseChangesToTermsMinimum
Namespace Prefix: | mfa_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Sales Commission of Gross Sales Price + References No definition available. + Details
Name: | mfa_SalesCommissionofGrossSalesPrice
Namespace Prefix: | mfa_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Shares Outstanding for Future Offerings + References No definition available. + Details
Name: | mfa_SharesOutstandingforFutureOfferings
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Shares Reclassified to Redeemable Capital Stock, Shares + References No definition available. + Details
Name: | mfa_SharesReclassifiedtoRedeemableCapitalStockShares
Namespace Prefix: | mfa_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition -- None. No documentation exists for this element. -- + References No definition available. + Details
Name: | mfa_StockholdersEquityLineItems
Namespace Prefix: | mfa_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 + Details
Name: | us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 + Details
Name: | us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Aggregate number of common shares reserved for future issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.29) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 + Details
Name: | us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition The maximum number of common shares permitted to be issued by an entity's charter and bylaws. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockSharesAuthorized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The percentage rate used to calculate dividend payments on preferred stock. + References No definition available. + Details
Name: | us-gaap_PreferredStockDividendRatePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Aggregate dividends declared during the period for each share of preferred stock outstanding. + References No definition available. + Details
Name: | us-gaap_PreferredStockDividendsPerShareDeclared
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition The per share liquidation preference (or restrictions) of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) that has a preference in involuntary liquidation considerably in excess of the par or stated value of the shares. The liquidation preference is the difference between the preference in liquidation and the par or stated values of the share. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(d)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21484-112644 + Details
Name: | us-gaap_PreferredStockLiquidationPreference
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_PreferredStockParOrStatedValuePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Per share amount of cumulative preferred dividends in arrears. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21488-112644 + Details
Name: | us-gaap_PreferredStockPerShareAmountsOfPreferredDividendsInArrears
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition The price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control of the issuer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21488-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21564-112644 + Details
Name: | us-gaap_PreferredStockRedemptionPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_PreferredStockSharesIssued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash inflow from issuance of preferred stock that is classified as callable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfRedeemablePreferredStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow from issuance of rights to purchase common shares at predetermined price (usually issued together with corporate debt). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfWarrants
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The number of shares issued or sold by the subsidiary or equity method investee per stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of shares issued during the period from a dividend reinvestment plan (DRIP). A dividend reinvestment plan allows the shareholders to reinvest dividends paid to them by the entity on new issues of stock by the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesDividendReinvestmentPlan
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Value of stock issued during the period from a dividend reinvestment plan (DRIP). A dividend reinvestment plan allows the holder of the stock to reinvest dividends paid to them by the entity on new issues of stock by the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueDividendReinvestmentPlan
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan. + References No definition available. + Details
Name: | us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan. + References No definition available. + Details
Name: | us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_PlanNameAxis=mfa_DiscountWaiverDirectStockPurchaseAndDividendReinvestmentPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesBPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesCPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_PreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_WarrantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=mfa_AtTheMarketMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=mfa_ExercisePriceRangeOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=mfa_ExercisePriceRangeTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_DebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |