Collateral Positions (Details 2) $ in Thousands	Jun. 30, 2016 USD ($)
Collateral Positions
Total Fair Value of Assets Pledged and Accrued Interest	$ 11,129,206
Agency MBS
Collateral Positions
Total Fair Value of Assets Pledged and Accrued Interest	4,085,155
Legacy Non-Agency MBS
Collateral Positions
Total Fair Value of Assets Pledged and Accrued Interest	2,620,879
RPL/NPL MBS
Collateral Positions
Total Fair Value of Assets Pledged and Accrued Interest	2,691,681
U.S. Treasuries
Collateral Positions
Total Fair Value of Assets Pledged and Accrued Interest	512,059
CRT securities
Collateral Positions
Total Fair Value of Assets Pledged and Accrued Interest	255,804
Residential Whole Loans
Collateral Positions
Total Fair Value of Assets Pledged and Accrued Interest	820,544
Cash
Collateral Positions
Total Fair Value of Assets Pledged and Accrued Interest	143,084
Repurchase Agreements and Other Advances
Collateral Positions
Fair Value	10,934,639
Amortized Cost	10,387,622
Accrued Interest on Pledged Assets	22,940
Repurchase Agreements and Other Advances \| Agency MBS
Collateral Positions
Fair Value	4,039,785
Amortized Cost	3,990,571
Accrued Interest on Pledged Assets	9,637
Repurchase Agreements and Other Advances \| Agency MBS \| FHLB Advances
Collateral Positions
Fair Value	585,100
Amortized Cost	576,000
Accrued Interest on Pledged Assets	1,400
Repurchase Agreements and Other Advances \| Legacy Non-Agency MBS
Collateral Positions
Fair Value	2,611,165
Amortized Cost	2,140,135
Accrued Interest on Pledged Assets	9,714
Non-Agency MBS acquired from consolidated VIEs in connection with resecuritization transactions	190,300
Non-Agency MBS pledged as collateral in connection with contemporaneous repurchase and reverse repurchase agreements entered into with a single counterparty	697,200
Repurchase Agreements and Other Advances \| RPL/NPL MBS
Collateral Positions
Fair Value	2,690,238
Amortized Cost	2,694,113
Accrued Interest on Pledged Assets	1,443
Repurchase Agreements and Other Advances \| U.S. Treasuries
Collateral Positions
Fair Value	512,059
Amortized Cost	512,059
Accrued Interest on Pledged Assets	0
Repurchase Agreements and Other Advances \| CRT securities
Collateral Positions
Fair Value	255,675
Amortized Cost	250,535
Accrued Interest on Pledged Assets	129
Repurchase Agreements and Other Advances \| Residential Whole Loans
Collateral Positions
Fair Value	818,527
Amortized Cost	793,019
Accrued Interest on Pledged Assets	2,017
Repurchase Agreements and Other Advances \| Cash
Collateral Positions
Fair Value	7,190
Amortized Cost	7,190
Accrued Interest on Pledged Assets	0
Derivative Hedging Instruments
Collateral Positions
Fair Value	171,555
Amortized Cost	171,547
Accrued Interest on Pledged Assets	72
Derivative Hedging Instruments \| Agency MBS
Collateral Positions
Fair Value	35,661
Amortized Cost	35,653
Accrued Interest on Pledged Assets	72
Derivative Hedging Instruments \| Legacy Non-Agency MBS
Collateral Positions
Fair Value	0
Amortized Cost	0
Accrued Interest on Pledged Assets	0
Derivative Hedging Instruments \| RPL/NPL MBS
Collateral Positions
Fair Value	0
Amortized Cost	0
Accrued Interest on Pledged Assets	0
Derivative Hedging Instruments \| U.S. Treasuries
Collateral Positions
Fair Value	0
Amortized Cost	0
Accrued Interest on Pledged Assets	0
Derivative Hedging Instruments \| CRT securities
Collateral Positions
Fair Value	0
Amortized Cost	0
Accrued Interest on Pledged Assets	0
Derivative Hedging Instruments \| Residential Whole Loans
Collateral Positions
Fair Value	0
Amortized Cost	0
Accrued Interest on Pledged Assets	0
Derivative Hedging Instruments \| Cash
Collateral Positions
Fair Value	135,894
Amortized Cost	135,894
Accrued Interest on Pledged Assets	$ 0

Represents the amount of interest receivable on securities pledged as collateral.

No definition available.

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Namespace Prefix:	mfa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

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- Definition

For an unclassified balance sheet, represents investments in debt and equity securities, categorized neither as held-to-maturity nor trading, which are acquired from a consolidated variable interest entity and eliminated on the entity's consolidated balance sheet.

+ References

No definition available.

+ Details

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Namespace Prefix:	mfa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the non-agency MBS pledged as collateral in connection with contemporaneous repurchase and reverse repurchase agreements entered into with a single counterparty.

+ References

No definition available.

+ Details

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- Definition

Sum of the fair values as of the date of the latest financial statement presented of securities pledged as collateral and the amount of interest receivable on the securities pledged as collateral.

+ References

No definition available.

+ Details

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Namespace Prefix:	mfa_
Data Type:	xbrli:monetaryItemType
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- Definition

Represents the cost of debt and equity securities pledged as collateral, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

No definition available.

+ Details

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Namespace Prefix:	mfa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

+ Details

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- Details

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- Details

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- Details

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