Investment in Loans (Schedule of Residential Mortgage Loans) (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		$ 1,414,410	$ 1,387,733
Unamortized Premium (Discount)		(202,583)	(150,821)
Fair Value	[1]	$ 1,442,612	$ 1,412,426
Weighted Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Coupon		3.98%	4.23%
Weighted Average Yield		4.89%	4.01%
Weighted average life		4 years 4 months 17 days	5 years 10 months 24 days
Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		$ 1,004,980	$ 911,705
Fair Value		1,030,709	932,203
Consolidated securitization trusts [Member] | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gains		17,500
Losses		200
Loans held-for-investment [Member] | Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		996,429	911,705
Unamortized Premium (Discount)		8,676	9,354
Amortized Cost		1,005,105	921,059
Gains		21,504	13,082
Losses		(4,355)	(1,938)
Fair Value		$ 1,022,254	$ 932,203
Loans held-for-investment [Member] | Residential mortgage loans | Weighted Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Coupon		6.23%	6.44%
Weighted Average Yield		5.15%	5.79%
Weighted average life		1 year 7 months 28 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		$ 760,420	$ 628,415

[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.