Investment in Securities (Maturities of Securities) (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)	[1],[2]	$ 1,909,127	$ 1,514,185
Amortized Cost		$ 1,815,909	$ 1,474,155
Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.68%	3.92%
Long
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 1,909,127	$ 1,514,185
Amortized Cost		$ 1,911,765	$ 1,508,997
Long | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.53%	3.84%
Long | Agency RMBS
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 1,438,731	$ 911,787
Amortized Cost		$ 1,430,113	$ 881,270
Long | Agency RMBS | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.22%	3.84%
Long | Agency RMBS | Less than three years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 79,755	$ 139,059
Amortized Cost		$ 77,736	$ 135,844
Long | Agency RMBS | Less than three years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		4.44%	4.15%
Long | Agency RMBS | Greater than three years less than seven years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 1,145,288	$ 770,173
Amortized Cost		$ 1,135,139	$ 742,946
Long | Agency RMBS | Greater than three years less than seven years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.27%	3.79%
Long | Agency RMBS | Greater than seven years less than eleven [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 213,688	$ 2,555
Amortized Cost		$ 217,238	$ 2,480
Long | Agency RMBS | Greater than seven years less than eleven [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		2.53%	3.01%
Long | Agency RMBS | Greater than eleven year [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 0	$ 0
Amortized Cost		$ 0	$ 0
Long | Agency RMBS | Greater than eleven year [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.00%	0.00%
Long | Agency RMBS | Interest only securities
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 49,051	$ 47,656
Amortized Cost		$ 44,867	$ 43,406
Long | Agency RMBS | Interest only securities | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.47%	3.36%
Long | Agency RMBS | Interest only securities | Less than three years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 6,335	$ 8,143
Amortized Cost		$ 5,597	$ 7,314
Long | Agency RMBS | Interest only securities | Less than three years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.81%	3.99%
Long | Agency RMBS | Interest only securities | Greater than three years less than seven years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 35,542	$ 32,669
Amortized Cost		$ 33,166	$ 29,362
Long | Agency RMBS | Interest only securities | Greater than three years less than seven years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.87%	3.74%
Long | Agency RMBS | Interest only securities | Greater than seven years less than eleven [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 4,416	$ 5,165
Amortized Cost		$ 4,269	$ 5,063
Long | Agency RMBS | Interest only securities | Greater than seven years less than eleven [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.84%	1.04%
Long | Agency RMBS | Interest only securities | Greater than eleven year [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 2,758	$ 1,679
Amortized Cost		$ 1,835	$ 1,667
Long | Agency RMBS | Interest only securities | Greater than eleven year [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		1.16%	0.83%
Long | Non-Agency RMBS and CMBS
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 235,243	$ 312,157
Amortized Cost		$ 233,525	$ 317,081
Long | Non-Agency RMBS and CMBS | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.88%	2.98%
Long | Non-Agency RMBS and CMBS | Less than three years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 56,973	$ 58,350
Amortized Cost		$ 54,090	$ 54,339
Long | Non-Agency RMBS and CMBS | Less than three years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.53%	3.39%
Long | Non-Agency RMBS and CMBS | Greater than three years less than seven years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 102,383	$ 114,815
Amortized Cost		$ 97,457	$ 109,161
Long | Non-Agency RMBS and CMBS | Greater than three years less than seven years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		4.85%	3.45%
Long | Non-Agency RMBS and CMBS | Greater than seven years less than eleven [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 56,309	$ 109,519
Amortized Cost		$ 61,353	$ 123,782
Long | Non-Agency RMBS and CMBS | Greater than seven years less than eleven [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		2.67%	2.74%
Long | Non-Agency RMBS and CMBS | Greater than eleven year [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 19,578	$ 29,473
Amortized Cost		$ 20,625	$ 29,799
Long | Non-Agency RMBS and CMBS | Greater than eleven year [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.79%	1.46%
Long | Non-Agency RMBS
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 196,613	$ 201,090
Amortized Cost		$ 189,650	$ 190,759
Long | Non-Agency RMBS | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		4.15%	3.15%
Long | Non-Agency RMBS | Interest only securities
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 10,589	$ 9,610
Amortized Cost		$ 8,918	$ 8,123
Long | Non-Agency RMBS | Interest only securities | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		1.08%	1.17%
Long | Non-Agency RMBS | Interest only securities | Less than three years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 4,649	$ 5,163
Amortized Cost		$ 3,333	$ 3,754
Long | Non-Agency RMBS | Interest only securities | Less than three years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.94%	0.92%
Long | Non-Agency RMBS | Interest only securities | Greater than three years less than seven years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 4,600	$ 4,447
Amortized Cost		$ 4,266	$ 4,369
Long | Non-Agency RMBS | Interest only securities | Greater than three years less than seven years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		1.44%	1.37%
Long | Non-Agency RMBS | Interest only securities | Greater than seven years less than eleven [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 0	$ 0
Amortized Cost		$ 0	$ 0
Long | Non-Agency RMBS | Interest only securities | Greater than seven years less than eleven [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.00%	0.00%
Long | Non-Agency RMBS | Interest only securities | Greater than eleven year [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 1,340	$ 0
Amortized Cost		$ 1,319	$ 0
Long | Non-Agency RMBS | Interest only securities | Greater than eleven year [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.30%	0.00%
Long | CLOs And Other Securities [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 171,393	$ 231,385
Amortized Cost		$ 190,812	$ 257,513
Long | CLOs And Other Securities [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		5.63%	5.09%
Long | CLOs And Other Securities [Member] | Less than three years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 100,024	$ 89,235
Amortized Cost		$ 105,291	$ 90,869
Long | CLOs And Other Securities [Member] | Less than three years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		6.89%	7.73%
Long | CLOs And Other Securities [Member] | Greater than three years less than seven years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 71,369	$ 139,830
Amortized Cost		$ 85,521	$ 163,670
Long | CLOs And Other Securities [Member] | Greater than three years less than seven years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		4.06%	3.69%
Long | CLOs And Other Securities [Member] | Greater than seven years less than eleven [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 0	$ 2,320
Amortized Cost		$ 0	$ 2,974
Long | CLOs And Other Securities [Member] | Greater than seven years less than eleven [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.00%	1.14%
Long | CLOs And Other Securities [Member] | Greater than eleven year [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 0	$ 0
Amortized Cost		$ 0	$ 0
Long | CLOs And Other Securities [Member] | Greater than eleven year [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.00%	0.00%

[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.