XML 53 R40.htm IDEA: XBRL DOCUMENT v3.21.1

Summary of Significant Accounting Policies (Financing Agreements) (Details)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Repurchase financing period, low end of range	1 month
Repurchase financing period, high end of range	6 months
Repurchase financings collateralized by residential whole loans, high end	12 months

X

- Definition

Repurchase Agreements Financing Collateralized, Period, High End of Range

+ References

No definition available.

+ Details

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

X

- Definition

Represents the high end of the range of the typical period for repurchase financing agreements.

+ References

No definition available.

+ Details

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

X

- Definition

Represents the low end of the range of the typical period for repurchase financing agreements.

+ References

No definition available.

+ Details

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

X

- References

No definition available.

+ Details

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