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

Represents the minimum percentage of annual taxable income which must be distributed to stockholders in order to comply with requirements of the federal tax law for treatment as a real estate investment trust.

No definition available.

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

Represents the forfeiture rate applied to equity based awards granted in 2009 and prior years for determining the fair value of the awards.

No definition available.

Name:	mfa_ShareBasedCompensationArrangementByShareBasedPaymentAwardForfeitureRate2009AndPrior
Namespace Prefix:	mfa_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the maximum 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardMarketConditionPeriodMaximum
Namespace Prefix:	mfa_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the minimum 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardMarketConditionPeriodMinimum
Namespace Prefix:	mfa_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

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

The maximum vesting term over 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.

No definition available.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriodMaximum
Namespace Prefix:	us-gaap_
Data Type:	us-types:dateStringItemType
Balance Type:	na
Period Type:	duration

The minimum vesting term over 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.

No definition available.