Cover - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2022	Feb. 15, 2023	Jun. 30, 2022
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	1-13991
Entity Registrant Name	MFA FINANCIAL, INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	13-3974868
Entity Address, Address Line One	One Vanderbilt Ave., 48th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10017
City Area Code	212
Local Phone Number	207-6400
Title of 12(g) Security	None
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1.1
Entity Common Stock, Shares Outstanding (in shares)		101,911,876
Documents Incorporated by Reference	Portions of the registrant’s proxy statement to be filed with the Securities and Exchange Commission in connection with the Annual Meeting of Stockholders scheduled to be held on or about June 6, 2023, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Entity Central Index Key	0001055160
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Common Stock
Entity Information [Line Items]
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	MFA
Security Exchange Name	NYSE
7.50% Series B Cumulative Redeemable Preferred Stock, par value $0.01 per share
Entity Information [Line Items]
Title of 12(b) Security	7.50% Series B Cumulative RedeemablePreferred Stock, par value $0.01 per share
Trading Symbol	MFA/PB
Security Exchange Name	NYSE
6.50% Series C Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock, par value $0.01 per share
Entity Information [Line Items]
Title of 12(b) Security	6.50% Series C Fixed-to-Floating Rate Cumulative RedeemablePreferred Stock, par value $0.01 per share
Trading Symbol	MFA/PC
Security Exchange Name	NYSE