XML 65 R52.htm IDEA: XBRL DOCUMENT
v3.21.1

Securities, at Fair Value (Narrative) (Details) - USD ($) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2021 | Mar. 31, 2020 | Dec. 31, 2020 | Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Minimum term of fixed rate mortgages underlying MBS | 15 years |  |  |
Maximum term of fixed rate mortgages underlying MBS | 30 years |  |  |
Allowance for loan loss | $ 63,244,000 | $ 218,011,000 | $ 86,833,000 | $ 3,025,000
Impairment and other losses on securities available-for-sale and other assets | 0 | 419,651,000 |  |
Securities, at fair value |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Securities, at fair value | 244,700,000 |  | 239,000,000.0 |
Amortized costs | 185,600,000 |  | 184,900,000 |
Gross unrealized gains | $ 59,100,000 |  | $ 54,000,000.0 |
Weighted average yield | 12.10% |  | 12.30% |
Weighted average to maturity | 8 years 2 months 12 days |  | 8 years 8 months 12 days |
Proceeds from sale of MSR | $ 136,800,000 |  |  |
Realized losses | 24,600,000 |  |  |
Impairment | 280,800,000 |  |  |
Non-Agency MBS |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Allowance for loan loss | $ 0 |  |  |
MBS and MSR-Related Assets |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Impairment and other losses on securities available-for-sale and other assets |  | $ 63,500,000 |  |
Minimum | RPL/NPL MBS |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate | 3.00% |  |  |
Debt instrument, coupon step-up period | 36 months |  |  |
Maximum | RPL/NPL MBS |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate | 4.00% |  |  |
Debt instrument, coupon step-up period | 48 months |  |  |

X
- Definition Debt Instrument, Coupon Step-Up Period + References No definition available. + Details
Name: | mfa_DebtInstrumentCouponStepUpPeriod
Namespace Prefix: | mfa_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, Amortized Costs + References No definition available. + Details
Name: | mfa_FinancialInstrumentsOwnedMortgagesMortgagebackedandAssetbackedSecuritiesAmortizedCosts
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, Gross Realized Losses + References No definition available. + Details
Name: | mfa_FinancialInstrumentsOwnedMortgagesMortgagebackedandAssetbackedSecuritiesGrossRealizedLosses
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, Gross Unrealized Gains + References No definition available. + Details
Name: | mfa_FinancialInstrumentsOwnedMortgagesMortgagebackedandAssetbackedSecuritiesGrossUnrealizedGains
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, Impairment + References No definition available. + Details
Name: | mfa_FinancialInstrumentsOwnedMortgagesMortgagebackedandAssetbackedSecuritiesImpairment
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, Weighted Average Yield + References No definition available. + Details
Name: | mfa_FinancialInstrumentsOwnedMortgagesMortgagebackedandAssetbackedSecuritiesWeightedAverageYield
Namespace Prefix: | mfa_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, Weighted Average to Maturity + References No definition available. + Details
Name: | mfa_FinancialInstrumentsOwnedMortgagesMortgagebackedandAssetbackedSecuritiesWeightedAveragetoMaturity
Namespace Prefix: | mfa_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Impairment and Other Losses On Securities Available-for-Sale And Other Assets + References No definition available. + Details
Name: | mfa_ImpairmentandOtherLossesOnSecuritiesAvailableforSaleAndOtherAssets
Namespace Prefix: | mfa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the minimum period of the fixed rate mortgages which act as security for mortgage backed securities in the entity's portfolio. + References No definition available. + Details
Name: | mfa_MortgageBackedSecuritiesPeriodOfFixedRateMortgagesMinimum
Namespace Prefix: | mfa_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Mortgage Backed Securities, Period of Fixed Rate Mortgages Maximum + References No definition available. + Details
Name: | mfa_MortgageBackedSecuritiesPeriodofFixedRateMortgagesMaximum
Namespace Prefix: | mfa_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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 fair value as of the balance sheet date of firm holdings in mortgages, mortgage backed securities (investment instruments that represent ownership of an undivided interest in a group of mortgages, where principal and interest from the individual mortgages are used to pay investors' principal and interest on the mortgage backed security) and asset-backed securities that are primarily paid from the cash flows of a discrete pool of receivables or other financial assets (such as credit-card receivables), either fixed or revolving, that by their terms convert into cash within a finite time period. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 940 -SubTopic 320 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=35711157&loc=d3e42546-110969 + Details
Name: | us-gaap_FinancialInstrumentsOwnedMortgagesMortgageBackedAndAssetBackedSecuritiesAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 The cash inflow from the sale of servicing rights, which contractually entitle the servicer to receive fees and ancillary revenues for performing billing, collection, disbursement and recordkeeping services in connection with a mortgage portfolio. Rights may be obtained via (1) acquisition or assumption of a servicing obligation that does not relate to financial assets of the servicer or its consolidated affiliates; or (2) by originating mortgage loans and then (a) transferring the loans to a Variable Interest Entity (VIE) in a transaction that meets the necessary transfer and classification requirements, or (b) transferring the loans in a transaction that meets the requirements for sale accounting. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719 + Details
Name: | us-gaap_ProceedsFromSaleOfMortgageServicingRightsMSR
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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: | us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=mfa_TermNotesbackedbyMSRRelatedCollateralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=mfa_MBSAndMSRRelatedAssetsMember
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: | us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesOtherMember
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: |