(Schedule of Reverse Repurchase Agreements by Maturity) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) counterparty		Dec. 31, 2019 USD ($) counterparty		Dec. 31, 2018 USD ($) counterparty
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	$ 1,496,931	[1]	$ 2,445,300	[1]	$ 1,498,849
Number of Counterparties with Outstanding Reverse Repurchase Agreements | counterparty	24		28		23
Total secured borrowings	$ 2,300,000		$ 3,200,000		$ 1,911,000
Agency RMBS
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	921,862		1,864,473		917,262
Agency RMBS | 30 Days or Less
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	265,556		511,996		245,956
Agency RMBS | 31-60 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	385,141		744,387		415,379
Agency RMBS | 61-90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	174,586		594,738		255,421
Agency RMBS | 91-120 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	0		10,270		506
Agency RMBS | 151 to 180 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	59,857		3,082
Agency RMBS | More Than 360 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	34,030		0
Agency RMBS | 121-150 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	2,692		0
U.S. Treasury securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements					273
U.S. Treasury securities | 30 Days or Less
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements					273
Credit
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	575,069		580,827
Credit | 30 Days or Less
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	37,795		16,549		30,426
Credit | 31-60 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	84,554		104,491		189,937
Credit | 61-90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	152,426		138,837		93,202
Credit | 91-120 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	89,931		0		26,222
Credit | 151 to 180 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	11,063		31,498		91,730
Credit | More Than 360 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	38,640		186,661		140,306
Credit | Total Credit Assets
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	94,248		95,331		581,314
Credit | 121-150 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	$ 66,412		$ 7,460		$ 9,491
Minimum
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	0.20%		0.15%		23.00%
Repurchase agreements, remaining days to maturity	4 days		2 days		2 days
Maximum
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	5.00%		5.20%		607.00%
Repurchase agreements, remaining days to maturity	516 days		882 days		871 days
Weighted Average
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	1.20%		2.37%		3.13%
Repurchase agreements, remaining days to maturity	94 days		91 days		122 days
Weighted Average | Agency RMBS
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	0.27%		1.98%		2.59%
Repurchase agreements, remaining days to maturity	57 days		48 days		47 days
Weighted Average | Agency RMBS | 30 Days or Less
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	0.28%		2.08%		2.46%
Repurchase agreements, remaining days to maturity	17 days		17 days		17 days
Weighted Average | Agency RMBS | 31-60 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	0.25%		1.93%		2.58%
Repurchase agreements, remaining days to maturity	44 days		47 days		46 days
Weighted Average | Agency RMBS | 61-90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	0.28%		1.96%		2.74%
Repurchase agreements, remaining days to maturity	70 days		76 days		76 days
Weighted Average | Agency RMBS | 91-120 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	0.00%		2.24%		3.31%
Repurchase agreements, remaining days to maturity	0 days		93 days		91 days
Weighted Average | Agency RMBS | 151 to 180 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	0.32%		2.67%
Repurchase agreements, remaining days to maturity	162 days		171 days
Weighted Average | Agency RMBS | More Than 360 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	0.32%		0.00%
Repurchase agreements, remaining days to maturity	252 days		0 days
Weighted Average | Agency RMBS | 121-150 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	0.27%		0.00%
Repurchase agreements, remaining days to maturity	126 days		0 days
Weighted Average | U.S. Treasury securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate					3.10%
Repurchase agreements, remaining days to maturity					2 days
Weighted Average | U.S. Treasury securities | 30 Days or Less
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate					3.10%
Repurchase agreements, remaining days to maturity					2 days
Weighted Average | Credit
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	2.69%		3.61%
Repurchase agreements, remaining days to maturity	155 days		229 days
Weighted Average | Credit | 30 Days or Less
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	2.11%		3.38%		2.55%
Repurchase agreements, remaining days to maturity	17 days		25 days		22 days
Weighted Average | Credit | 31-60 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	2.23%		3.14%		3.32%
Repurchase agreements, remaining days to maturity	50 days		48 days		48 days
Weighted Average | Credit | 61-90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	2.11%		3.03%		3.21%
Repurchase agreements, remaining days to maturity	75 days		73 days		74 days
Weighted Average | Credit | 91-120 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	2.47%		0.00%		4.60%
Repurchase agreements, remaining days to maturity	106 days		0 days		123 days
Weighted Average | Credit | 151 to 180 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	2.27%		3.87%		4.54%
Repurchase agreements, remaining days to maturity	165 days		173 days		316 days
Weighted Average | Credit | More Than 360 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	2.90%		3.80%		5.15%
Repurchase agreements, remaining days to maturity	289 days		250 days		636 days
Weighted Average | Credit | Total Credit Assets
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	2.99%		4.52%		3.98%
Repurchase agreements, remaining days to maturity	447 days		678 days		240 days
Weighted Average | Credit | 121-150 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate	4.75%		3.89%		4.64%
Repurchase agreements, remaining days to maturity	125 days		123 days		166 days

[1] Ellington Financial Inc.'s 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.