XML 135 R115.htm IDEA: XBRL DOCUMENT
v3.20.4

Schedule IV - Mortgage Loans on Real Estate (Details) $ in Thousands | 12 Months Ended |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2020 USD ($) loan | Dec. 31, 2019 USD ($) | Sep. 30, 2020 USD ($) | Jun. 30, 2020 USD ($) | Mar. 31, 2020 USD ($) | Sep. 30, 2019 USD ($) | Jun. 30, 2019 USD ($) | Mar. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Allowance for credit loss | $ 86,833 | $ 3,025 | $ 106,246 | $ 136,589 | $ 218,011 | $ 2,271 | $ 1,986 | $ 1,651 | $ 968
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward] |  |  |  |  |  |  |  |  |
Residential whole loans, at carrying value, beginning balance | 698,717 |  |  |  |  |  |  |  |
Residential whole loans, at fair value, beginning balance | 1,381,583 |  |  |  |  |  |  |  |
Residential whole loans, at carrying value, ending balance | 673,708 | 698,717 |  |  |  |  |  |  |
Residential whole loans, at fair value, ending balance | $ 1,216,902 | 1,381,583 |  |  |  |  |  |  |
Residential whole loans, at fair value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 18,734 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 5,412,234 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | 1,080,733 |  |  |  |  |  |  |  |
Tax basis of loans | $ 3,900,000 |  |  |  |  |  |  |  |
Residential whole loans, at fair value | Carrying value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 13,112 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 4,195,332 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | 455,112 |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward] |  |  |  |  |  |  |  |  |
Residential whole loans, at carrying value, beginning balance | 6,066,345 |  |  |  |  |  |  |  |
Purchases | 1,431,673 |  |  |  |  |  |  |  |
Repayments | (1,565,553) |  |  |  |  |  |  |  |
Premium amortization/discount accretion, net | (11,590) |  |  |  |  |  |  |  |
Provision for loan loss | (21,447) |  |  |  |  |  |  |  |
Loan sales and repurchases | (1,766,220) |  |  |  |  |  |  |  |
Transfer to REO | (24,709) |  |  |  |  |  |  |  |
Residential whole loans, at carrying value, ending balance | $ 4,108,499 | 6,066,345 |  |  |  |  |  |  |
Residential whole loans, at fair value | Fair value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 5,622 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 1,216,902 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | 625,621 |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward] |  |  |  |  |  |  |  |  |
Residential whole loans, at fair value, beginning balance | 1,381,583 |  |  |  |  |  |  |  |
Purchases | 0 |  |  |  |  |  |  |  |
Changes in unrealized gains | 17,204 |  |  |  |  |  |  |  |
Repayments | (92,733) |  |  |  |  |  |  |  |
Repurchases | (18,530) |  |  |  |  |  |  |  |
Transfer to REO | (70,622) |  |  |  |  |  |  |  |
Residential whole loans, at fair value, ending balance | $ 1,216,902 | $ 1,381,583 |  |  |  |  |  |  |
Original loan balance $0 - $149,999 | Residential whole loans, at fair value | Carrying value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 3,947 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 347,041 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | $ 29,614 |  |  |  |  |  |  |  |
Original loan balance $0 - $149,999 | Residential whole loans, at fair value | Carrying value | Minimum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 0.00% |  |  |  |  |  |  |  |
Original loan balance $0 - $149,999 | Residential whole loans, at fair value | Carrying value | Maximum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 16.00% |  |  |  |  |  |  |  |
Original loan balance $0 - $149,999 | Residential whole loans, at fair value | Fair value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 2,044 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 167,671 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | $ 70,748 |  |  |  |  |  |  |  |
Original loan balance $0 - $149,999 | Residential whole loans, at fair value | Fair value | Minimum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 0.00% |  |  |  |  |  |  |  |
Original loan balance $0 - $149,999 | Residential whole loans, at fair value | Fair value | Maximum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 14.13% |  |  |  |  |  |  |  |
Original loan balance $150,000 - $299,999 | Residential whole loans, at fair value | Carrying value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 4,341 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 832,365 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | $ 73,749 |  |  |  |  |  |  |  |
Original loan balance $150,000 - $299,999 | Residential whole loans, at fair value | Carrying value | Minimum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 0.00% |  |  |  |  |  |  |  |
Original loan balance $150,000 - $299,999 | Residential whole loans, at fair value | Carrying value | Maximum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 13.49% |  |  |  |  |  |  |  |
Original loan balance $150,000 - $299,999 | Residential whole loans, at fair value | Fair value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 1,909 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 355,854 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | $ 167,303 |  |  |  |  |  |  |  |
Original loan balance $150,000 - $299,999 | Residential whole loans, at fair value | Fair value | Minimum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 1.95% |  |  |  |  |  |  |  |
Original loan balance $150,000 - $299,999 | Residential whole loans, at fair value | Fair value | Maximum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 11.53% |  |  |  |  |  |  |  |
Original loan balance $300,000 - $449,999 | Residential whole loans, at fair value | Carrying value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 2,064 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 667,272 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | $ 65,629 |  |  |  |  |  |  |  |
Original loan balance $300,000 - $449,999 | Residential whole loans, at fair value | Carrying value | Minimum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 1.50% |  |  |  |  |  |  |  |
Original loan balance $300,000 - $449,999 | Residential whole loans, at fair value | Carrying value | Maximum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 9.63% |  |  |  |  |  |  |  |
Original loan balance $300,000 - $449,999 | Residential whole loans, at fair value | Fair value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 1,000 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 313,588 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | $ 165,901 |  |  |  |  |  |  |  |
Original loan balance $300,000 - $449,999 | Residential whole loans, at fair value | Fair value | Minimum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 0.00% |  |  |  |  |  |  |  |
Original loan balance $300,000 - $449,999 | Residential whole loans, at fair value | Fair value | Maximum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 10.75% |  |  |  |  |  |  |  |
Original loan balance greater than $449,999 | Residential whole loans, at fair value | Carrying value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 2,760 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 2,348,654 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | $ 286,120 |  |  |  |  |  |  |  |
Original loan balance greater than $449,999 | Residential whole loans, at fair value | Carrying value | Minimum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 0.88% |  |  |  |  |  |  |  |
Original loan balance greater than $449,999 | Residential whole loans, at fair value | Carrying value | Maximum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 11.25% |  |  |  |  |  |  |  |
Original loan balance greater than $449,999 | Residential whole loans, at fair value | Fair value |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Number | loan | 669 |  |  |  |  |  |  |  |
Balance Sheet Reported Amount | $ 379,789 |  |  |  |  |  |  |  |
Principal Amount of Loans Subject to Delinquent Principal or Interest | $ 221,669 |  |  |  |  |  |  |  |
Original loan balance greater than $449,999 | Residential whole loans, at fair value | Fair value | Minimum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 1.70% |  |  |  |  |  |  |  |
Original loan balance greater than $449,999 | Residential whole loans, at fair value | Fair value | Maximum |  |  |  |  |  |  |  |  |
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items] |  |  |  |  |  |  |  |  |
Interest Rate | 10.20% |  |  |  |  |  |  |  |

X
- Definition Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Tax Basis + References No definition available. + Details
Name: | mfa_CertainLoansAcquiredinTransferNotAccountedforasDebtSecuritiesTaxBasis
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Repurchases + References No definition available. + Details
Name: | mfa_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetValueRepurchases
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Mortgage Loans on Real Estate, Amortization (Discount) Accretion, Net + References No definition available. + Details
Name: | mfa_MortgageLoansOnRealEstateAmortizationDiscountAccretionNet
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Mortgage Loans on Real Estate, Provision for Loan Loss + References No definition available. + Details
Name: | mfa_MortgageLoansonRealEstateProvisionforLoanLoss
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Mortgage Loans on Real Estate, Repurchases + References No definition available. + Details
Name: | mfa_MortgageLoansonRealEstateRepurchases
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Mortgage Loans on Real Estate, Transfer to REO + References No definition available. + Details
Name: | mfa_MortgageLoansonRealEstateTransfertoREO
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of decrease in investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, from collection of principal. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12 -Footnote 6 -Subsection 29 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29(Footnote 6)) -URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014 + Details
Name: | srt_MortgageLoansOnRealEstateCollectionsOfPrincipal
Namespace Prefix: | srt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Interest rate of mortgage loan within investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12 -Paragraph Column B -Subsection 29 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29(Column B)) -URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014 + Details
Name: | srt_MortgageLoansOnRealEstateInterestRate
Namespace Prefix: | srt_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | srt_MortgageLoansOnRealEstateLineItems
Namespace Prefix: | srt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of mortgage loans within investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12 -Footnote 3 -Subsection 29 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29(Footnote 3)) -URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014 + Details
Name: | srt_MortgageLoansOnRealEstateNumberOfLoans
Namespace Prefix: | srt_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of principal due on delinquent mortgage loan within investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12 -Paragraph Column H -Subsection 29 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29(Column H)) -URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014 + Details
Name: | srt_MortgageLoansOnRealEstatePrincipalAmountOfDelinquentLoans
Namespace Prefix: | srt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121585399&loc=d3e13503-111538 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodAtAcquisitionAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121585399&loc=d3e13503-111538 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesCarryingAmountNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121585399&loc=d3e13503-111538 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesOutstandingBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(7)(2)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of increase in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, from new investment. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29(Footnote 6)) -URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014 + Details
Name: | us-gaap_MortgageLoansOnRealEstateNewMortgageLoans
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_MovementInMortgageLoansOnRealEstateRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_LoansReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_PortionAtOtherThanFairValueFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mfa_MortgageLoansonRealEstateLoanBalanceAxis=mfa_OriginalLoanBalanceRange1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mfa_MortgageLoansonRealEstateLoanBalanceAxis=mfa_OriginalLoanBalanceRange2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mfa_MortgageLoansonRealEstateLoanBalanceAxis=mfa_OriginalLoanBalanceRange3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mfa_MortgageLoansonRealEstateLoanBalanceAxis=mfa_OriginalLoanBalanceRange4Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |