Investment in Loans (Schedule of Commercial Mortgage Loans) (Details) (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		$ 1,230,004
Unamortized Premium (Discount)		(106,592)
Amortized Cost			$ 2,970,306
Loans, at fair value	[1]	$ 1,225,843
Weighted Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Coupon		4.25%
Weighted Average Yield		4.24%
Weighted average life		5 years 128 days
Commercial mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance		$ 285,252
Unamortized Premium (Discount)		(25,055)
Amortized Cost		260,197
Gains		512
Losses		(83)
Loans, at fair value		$ 260,626
Commercial mortgage loans | Weighted Average
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Coupon		8.48%
Weighted Average Yield		9.24%
Weighted average life		1 year 7 days
Non-accrual status [Member] | Commercial mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value		$ 10,700

[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.