Borrowings (Details) $ in Thousands				3 Months Ended		12 Months Ended
		Feb. 13, 2019 USD ($)	Aug. 18, 2017 USD ($)	Mar. 31, 2019 USD ($) counterparty		Dec. 31, 2018 USD ($) counterparty	Mar. 31, 2018 USD ($)
Borrowings [Line Items]
Total secured borrowings				$ 1,949,000		$ 1,911,000
Concentration Risk, Reverse Repurchase Agreements						21.00%
Number of Counterparties With Concentration Risk, Reverse Repurchase Agreements | counterparty						1
Number of Counterparties with Outstanding Reverse Repurchase Agreements | counterparty				24		23
Investments held with dealers as collateral				$ 1,850,000		$ 1,790,000
Pledged Financial Instruments, Not Separately Reported, Securities For Repurchase Agreements Unsettled				$ 20,700		$ 86,700	$ 86,700
Repurchase Agreements amount at risk threshold				10.00%		10.00%
Other secured borrowings				$ 117,315	[1]	$ 114,100
Minimum
Borrowings [Line Items]
Reverse Repurchase Agreements Maturity				30 days		30 days
Reverse Repurchase Agreements Remaining Terms				1 day		2 days
Reverse Repurchase Agreements Interest Rate				0.24%		0.23%
Maximum
Borrowings [Line Items]
Reverse Repurchase Agreements Maturity				180 days		180 days
Reverse Repurchase Agreements Remaining Terms				781 days		871 days
Reverse Repurchase Agreements Interest Rate				5.85%		6.07%
Reverse repurchase agreements
Borrowings [Line Items]
Cash collateral posted for securities sold under agreements to repurchase	[2],[3]			$ 13,900		$ 17,000
Security Owned and Pledged as Collateral, Fair Value				200		200
Securitized residential mortgage loans
Borrowings [Line Items]
Fair Value of Assets Transfered and Accounted for as Secured Borrowings				296,400		314,200
Secured borrowing recourse facility collateralized by unsecured loan portfolio
Borrowings [Line Items]
Other secured borrowings				$ 11,400		$ 13,200
Effective interest rate on borrowing				4.75%		4.72%
Secured borrowing recourse facility collateralized by unsecured loan portfolio | Unsecured loans
Borrowings [Line Items]
Fair Value of Assets Transfered and Accounted for as Secured Borrowings				$ 20,200		$ 20,300
Non-QM loan securitization
Borrowings [Line Items]
Other secured borrowings				$ 282,100		$ 297,900
Effective interest rate on borrowing				3.75%		3.72%
Secured borrowing facility collateralized by unsecured loan portfolio
Borrowings [Line Items]
Other secured borrowings				$ 105,900		$ 101,000
Effective interest rate on borrowing				4.67%		4.68%
Secured borrowing facility collateralized by unsecured loan portfolio | Unsecured loans
Borrowings [Line Items]
Fair Value of Assets Transfered and Accounted for as Secured Borrowings				$ 157,100		$ 149,000
Senior Notes
Borrowings [Line Items]
Debt Instrument, Face Amount		$ 86,000	$ 86,000
Proceeds from Debt, Net of Issuance Costs			$ 84,700
Debt Instrument, Interest Rate, Stated Percentage		5.50%	5.25%
Redemption percentage		100.00%	100.00%
Debt Instrument, Maturity Date			Sep. 01, 2022
Effective interest rate on borrowing				5.80%		5.55%

[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] For the purpose of this presentation, for each row the total amount of financial instruments transferred or pledged and cash collateral (received) or pledged may not exceed the applicable gross amount of assets or (liabilities) as presented here. Therefore, the Company has reduced the amount of financial instruments transferred or pledged as collateral related to the Company's reverse repurchase agreements and cash collateral pledged on the Company's financial derivative liabilities. Total financial instruments transferred or pledged as collateral on the Company's reverse repurchase agreements as of December 31, 2018 were $1.79 billion. As of December 31, 2018 total cash collateral on financial derivative assets excludes excess net cash collateral pledged of $0.1 million. As of December 31, 2018 total cash collateral on financial derivative liabilities excludes excess cash collateral pledged of $16.4 million

[3] When collateral is pledged to or pledged by a counterparty, it is often pledged or posted with respect to all positions with such counterparty, and in such cases such collateral cannot be specifically identified as relating to a specific asset or liability. As a result, in preparing the above tables, the Company has made assumptions in allocating pledged or posted collateral among the various rows.