Name:	mfa_NumberOfComponentsOfLinkedTransactions
Namespace Prefix:	mfa_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of annual REIT taxable income that the entity intends to distribute to its stockholders.

No definition available.

Name:	mfa_PercentageOfAnnualREITTaxableIncomeDistributedToStockholders
Namespace Prefix:	mfa_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the period over which changes in the entity's closing stock price and dividends declared on the entity's common stock are measured to determine stockholder returns that represent a market condition upon which an employee's right to exercise an award is contingent.

No definition available.

Name:	mfa_ShareBasedCompensationArrangementByShareBasedPaymentAwardMarketConditionPeriod
Namespace Prefix:	mfa_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Share Based Compensation Arrangement by Share Based Payment Award, Forfeiture Rate, Prior Years

No definition available.

Name:	mfa_ShareBasedCompensationArrangementbyShareBasedPaymentAwardForfeitureRatePriorYears
Namespace Prefix:	mfa_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	us-gaap_DerivativeInstrumentDetailAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	us-gaap_IncomeTaxDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a),(b)
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Income Tax Expense (or Benefit)
-URI http://asc.fasb.org/extlink&oid=6515339

Name:	us-gaap_IncomeTaxExpenseBenefit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.