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

Represents the percentage of the employer's matching contribution on the first tier of eligible compensation deferred by employees.

No definition available.

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

Represents the percentage of the employer's matching contribution on the second tier of eligible compensation deferred by employees.

No definition available.

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

Represents the percentage of the first tier of eligible compensation deferred by employees and receiving the highest level of employer match.

No definition available.

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

Represents the percentage of the second tier of eligible compensation deferred by employees and receiving the second level of employer match.

No definition available.

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

Represents undistributed income deferred by participants under a deferred compensation arrangement as of the balance sheet date.

No definition available.

Name:	mfa_DeferredCompensationArrangementWithIndividualUndistributedIncomeDeferred
Namespace Prefix:	mfa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The percentage of employer matching contributions under a deferred compensation arrangement that vest immediately.

No definition available.

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

The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

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

Amount of contributions made by employer into fund established for purposes of making future disbursement to individual in accordance with deferred compensation arrangement.

No definition available.

Name:	us-gaap_DeferredCompensationArrangementWithIndividualContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The carrying amount of the liability as of the balance sheet date to an individual under a deferred compensation arrangement. This amount may be the result of periodic accruals made over the period of active employment, or reflect termination benefits resulting contractual terms or a death benefit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

Name:	us-gaap_DeferredCompensationArrangementWithIndividualRecordedLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.