Entity Information - $ / shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019	Dec. 31, 2018
Entity Information [Line Items]
Entity Registrant Name	DYNEX CAPITAL INC
Entity Central Index Key	0000826675
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Common Stock, Shares Outstanding		73,763,826
Entity Emerging Growth Company	false
Common stock, par value	$ 0.01		$ 0.01