Valuation (Fair Value of Other Financial Instruments) (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2021	Dec. 31, 2020
Assets:
Cash and cash equivalents	[1]	$ 103,617	$ 111,647
Due from brokers		89,983	63,147
Reverse repurchase agreements		38,062	38,640
Liabilities:
Repurchase agreements	[1]	2,105,836	1,496,931
Other secured borrowings	[1]	90,981	51,062
Senior notes, net		85,759	85,561
Due to brokers		2,560	5,059
Credit Default Swap, Selling Protection [Member]
Liabilities:
Total net up-front payments received		800	(2,000)
Fair Value
Assets:
Cash and cash equivalents		103,617	111,647
Restricted cash		175	175
Due from brokers		89,983	63,147
Reverse repurchase agreements		38,062	38,640
Liabilities:
Repurchase agreements		2,105,836	1,496,931
Other secured borrowings		90,981	51,062
Senior notes, net		86,490	86,000
Due to brokers		2,560	5,059
Carrying Value
Assets:
Cash and cash equivalents		103,617	111,647
Restricted cash		175	175
Due from brokers		89,983	63,147
Reverse repurchase agreements		38,062	38,640
Liabilities:
Repurchase agreements		2,105,836	1,496,931
Other secured borrowings		90,981	51,062
Senior notes, net		85,759	85,561
Due to brokers		$ 2,560	$ 5,059

[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.