Investment in Loans (Schedule of Residential Mortgage Loans) (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		$ 1,536,714	$ 1,417,054
Unamortized Premium (Discount)		(156,693)	(196,118)
Fair Value	[1],[2]	$ 1,582,516	$ 1,453,480
Weighted Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Coupon		3.68%	3.92%
Weighted Average Yield		3.62%	4.77%
Weighted average life		5 years 4 months 17 days	4 years 5 months 26 days
Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		$ 1,236,923	$ 1,150,303
Fair Value		1,280,637	1,187,069
Residential mortgage loans | Non-performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		53,289	62,009
Fair Value		49,586	58,169
Consolidated securitization trusts [Member] | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gains		27,500	24,800
Losses		200	100
Loans held-for-investment [Member] | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		1,236,923	1,150,303
Unamortized Premium (Discount)		18,997	14,263
Amortized Cost		1,255,920	1,164,566
Gains		29,604	27,892
Losses		(4,887)	(5,389)
Fair Value		$ 1,280,637	$ 1,187,069
Loans held-for-investment [Member] | Residential mortgage loans | Weighted Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Coupon		6.12%	6.19%
Weighted Average Yield		4.21%	5.60%
Weighted average life		1 year 4 months 2 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		$ 961,332	$ 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.