Investment in Loans (Schedule of Residential Mortgage Loans) (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		$ 1,940,279	$ 1,417,054
Unamortized Premium (Discount)		(143,084)	(196,118)
Fair Value	[1],[2]	$ 1,996,529	$ 1,453,480
Weighted Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Coupon		3.63%	3.92%
Weighted Average Yield		3.45%	4.77%
Weighted average life		5 years 11 months 4 days	4 years 5 months 26 days
Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		$ 1,602,548	$ 1,150,303
Fair Value		1,656,701	1,187,069
Residential mortgage loans | Non-performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		34,904	62,009
Fair Value		32,107	58,169
Consolidated securitization trusts [Member] | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gains		20,400	24,800
Losses		400	100
Loans held-for-investment [Member] | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		1,602,548	1,150,303
Unamortized Premium (Discount)		34,431	14,263
Amortized Cost		1,636,979	1,164,566
Gains		25,125	27,892
Losses		(5,403)	(5,389)
Fair Value		$ 1,656,701	$ 1,187,069
Loans held-for-investment [Member] | Residential mortgage loans | Weighted Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Coupon		5.79%	6.19%
Weighted Average Yield		4.56%	5.60%
Weighted average life		1 year 11 months 12 days	1 year 10 months 24 days
Non-QM loan securitization | Residential mortgage loans | Consolidated Entities [Member] | Securitized loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value		$ 917,275	$ 801,343

[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.