COVER PAGE - shares	9 Months Ended
	Sep. 30, 2023	Oct. 31, 2023
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
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
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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		101,915,797
Entity Central Index Key	0001055160
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Common Stock, par value $0.01 per share
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