(Schedule of Reverse Repurchase Agreements by Maturity) (Details) $ in Thousands		3 Months Ended	9 Months Ended	12 Months Ended
		Mar. 31, 2020	Sep. 30, 2020 USD ($) counterparty	Dec. 31, 2019 USD ($) counterparty
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	[1]		$ 1,439,984	$ 2,445,300
Number of Counterparties with Outstanding Reverse Repurchase Agreements | counterparty			24	28
Total secured borrowings			$ 2,300,000	$ 3,200,000
Agency RMBS
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			883,786	1,864,473
Agency RMBS | 30 Days or Less
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			241,423	511,996
Agency RMBS | 31-60 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			418,573	744,387
Agency RMBS | 61-90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			107,446	594,738
Agency RMBS | 91-120 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			5,675	10,270
Agency RMBS | 151 to 180 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			17,237	3,082
Agency RMBS | More Than 360 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			93,432	0
Credit
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			556,198	580,827
Credit | 30 Days or Less
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			40,785	16,549
Credit | 31-60 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			98,068	104,491
Credit | 61-90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			113,027	138,837
Credit | 91-120 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			154,379	0
Credit | 121-150 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			6,015	7,460
Credit | 151 to 180 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			13,750	31,498
Credit | More Than 360 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			81,933	186,661
Credit | Total Credit Assets
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements			$ 48,241	$ 95,331
Minimum
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			0.22%	0.15%
Repurchase agreements, remaining days to maturity		2 days	1 day
Maximum
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			5.24%	5.20%
Repurchase agreements, remaining days to maturity		882 days	608 days
Weighted Average
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			1.37%	2.37%
Repurchase agreements, remaining days to maturity			98 days	91 days
Weighted Average | Agency RMBS
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			0.31%	1.98%
Repurchase agreements, remaining days to maturity			69 days	48 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			0.31%	2.08%
Repurchase agreements, remaining days to maturity			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			0.27%	1.93%
Repurchase agreements, remaining days to maturity			44 days	47 days
Weighted Average | Agency RMBS | 61-90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			0.45%	1.96%
Repurchase agreements, remaining days to maturity			72 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			1.35%	2.24%
Repurchase agreements, remaining days to maturity			99 days	93 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			0.29%	2.67%
Repurchase agreements, remaining days to maturity			168 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			0.30%	0.00%
Repurchase agreements, remaining days to maturity		0 days	287 days
Weighted Average | Credit
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			3.04%	3.61%
Repurchase agreements, remaining days to maturity			145 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			2.14%	3.38%
Repurchase agreements, remaining days to maturity			10 days	25 days
Weighted Average | Credit | 31-60 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			2.85%	3.14%
Repurchase agreements, remaining days to maturity			45 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			2.54%	3.03%
Repurchase agreements, remaining days to maturity			77 days	73 days
Weighted Average | Credit | 91-120 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			2.79%	0.00%
Repurchase agreements, remaining days to maturity		0 days	106 days
Weighted Average | Credit | 121-150 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			3.29%	3.89%
Repurchase agreements, remaining days to maturity			134 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			3.23%	3.87%
Repurchase agreements, remaining days to maturity			167 days	173 days
Weighted Average | Credit | More Than 360 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			4.83%	3.80%
Repurchase agreements, remaining days to maturity			228 days	250 days
Weighted Average | Credit | Total Credit Assets
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase Agreements Interest Rate			3.05%	4.52%
Repurchase agreements, remaining days to maturity			608 days	678 days

[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.