Investment in Loans (Narrative) (Details) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2021 USD ($) loan	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) loan	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	[1],[2]	$ 1,996,529		$ 1,996,529		$ 1,453,480
Unpaid Principal Balance		1,940,279		1,940,279		1,417,054
Commercial mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value		267,591		267,591		213,031
Losses		(173)		(173)		(454)
Financing Receivable, Allowance for Credit Loss		400		400		400
Mortgage Loans in Process of Foreclosure, Amount						10,500
Unpaid Principal Balance		267,388		267,388		$ 212,716
Number of mortgage loans in process of foreclosure						1
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value		55,676		55,676		$ 47,525
Losses		(1,154)		(1,154)		(1,887)
Unpaid Principal Balance		53,515		53,515		48,180
Delinquent loans, charged off		500	$ 3,900	2,900	$ 13,900
Financing Receivable, Allowance for Credit Loss				1,000		2,900
Fair value of charged-off loans		300		300		600
Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value		1,656,701		1,656,701		1,187,069
Mortgage Loans in Process of Foreclosure, Amount		12,900		12,900		14,900
Unpaid Principal Balance		1,602,548		1,602,548		1,150,303
Non-performing | Commercial mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value		$ 40,000		$ 40,000		$ 31,500
Number of loans | loan		6		6		3
Unpaid Principal Balance		$ 39,800		$ 39,800		$ 31,800
Non-performing | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value		32,107		32,107		58,169
Unpaid Principal Balance		34,904		34,904		62,009
Loans held-for-investment [Member] | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Realized Losses, Write offs on loans				(1,400)
Loans held-for-investment [Member] | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value		1,656,701		1,656,701		1,187,069
Losses		(5,403)		(5,403)		(5,389)
Financing Receivable, Allowance for Credit Loss		1,500		1,500		2,200
Unpaid Principal Balance		$ 1,602,548		1,602,548		1,150,303
Realized Losses, Write offs on loans			$ (51)	(33)	$ (500)
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date				$ 200		$ 200

[1] Ellington Financial Inc.'s Condensed 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.

[2] Includes assets pledged as collateral to counterparties. See Note 11 for additional details on the Company's borrowings and related collateral.