To Be Announced RMBS (Details) - USD ($) $ in Thousands	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
To Be Announced Securities [Line Items]
Fair Value					$ 2,939,311
Unpaid Principal Balance	$ 1,417,054		$ 1,387,733
Investments sold short, at fair value-	(38,642)		(73,409)		(850,577)
Payable for securities purchased relating to unsettled TBA purchases	(4,754)	[1]	(66,133)	[1]	(488,411)
Net short TBA securities, at fair value	$ (1,475,543)		(2,376,532)
To Be Announced Fixed Rate Agency Securities [Member]
To Be Announced Securities [Line Items]
Fair Value					474,860
Unpaid Principal Balance			460,037
Receivable for securities sold relating to unsettled TBA sales					766,574
TBA - Fixed Rate Agency Securities Sold Short [Member]
To Be Announced Securities [Line Items]
Investments sold short, at fair value-					(772,964)
Current Principal			$ (753,697)
Payable for securities purchased relating to unsettled TBA purchases					(473,386)
Net short TBA securities, at fair value					$ (298,104)

[1] Ellington Financial Inc.'s Consolidated Balance Sheet includes assets and liabilities of variable interest entities it has consolidated. See Note 9 for additional details on Ellington Financial Inc.'s consolidated variable interest entities.