Document and Entity Information Document and Entity Information - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Apr. 24, 2026
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2026
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-09819
Entity Registrant Name	DYNEX CAPITAL, INC.
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	52-1549373
Entity Address, Address Line One	140 Eastshore Drive
Entity Address, Address Line Two	Suite 100
Entity Address, City or Town	Glen Allen,
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	23059-5755
City Area Code	(804)
Local Phone Number	217-5800
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 Central Index Key	0000826675
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding			215,150,907
Other comprehensive income (loss)	$ (148)	$ 19,390
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	DX
Security Exchange Name	NYSE
Series C Preferred Stock
Document Information [Line Items]
Title of 12(b) Security	6.900% Series C Fixed-to-Floating Rate Cumulative Redeemable Preferred Stock, par value $0.01 per share
Trading Symbol	DXPRC
Security Exchange Name	NYSE