OFFSETTING ASSETS AND LIABILITIES - Offsetting of Liabilties (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Offsetting Liabilities [Line Items]
Gross Amount Of Recognized Liabilties	$ 4,489,644	$ 6,251,695
Gross Amount Of Liabilties Offset In The Balance Sheet	0	0
Net Amount Of Liabilities Presented In The Balance Sheet	4,489,644	6,251,695
Gross Amount Of Financial Instruments Posted Not Offset in Balance Sheet	(4,350,520)	(6,189,704)
Gross Amounts Of Cash Posted Not Offset In Balance Sheet	(113,589)	(57,264)
Net Amount Of Liabilities	25,535	4,727
Repurchase Agreement [Member]
Offsetting Liabilities [Line Items]
Gross Amount Of Recognized Liabilties	4,464,109	6,244,106
Gross Amount Of Liabilties Offset In The Balance Sheet	0	0
Net Amount Of Liabilities Presented In The Balance Sheet	4,464,109	6,244,106
Gross Amount Of Financial Instruments Posted Not Offset in Balance Sheet	(4,350,520)	(6,186,842)
Gross Amounts Of Cash Posted Not Offset In Balance Sheet	(113,589)	(57,264)
Net Amount Of Liabilities	0	0
Swap [Member]
Offsetting Liabilities [Line Items]
Gross Amount Of Recognized Liabilties		2,862
Gross Amount Of Liabilties Offset In The Balance Sheet		0
Net Amount Of Liabilities Presented In The Balance Sheet		2,862
Gross Amount Of Financial Instruments Posted Not Offset in Balance Sheet		(2,862)
Gross Amounts Of Cash Posted Not Offset In Balance Sheet		0
Net Amount Of Liabilities		0
TBA securities [Member]
Offsetting Liabilities [Line Items]
Gross Amount Of Recognized Liabilties		304
Gross Amount Of Liabilties Offset In The Balance Sheet		0
Net Amount Of Liabilities Presented In The Balance Sheet		304
Gross Amount Of Financial Instruments Posted Not Offset in Balance Sheet		0
Gross Amounts Of Cash Posted Not Offset In Balance Sheet		0
Net Amount Of Liabilities		304
Payer Swaption [Member]
Offsetting Liabilities [Line Items]
Gross Amount Of Recognized Liabilties	25,535	4,423
Gross Amount Of Liabilties Offset In The Balance Sheet	0	0
Net Amount Of Liabilities Presented In The Balance Sheet	25,535	4,423
Gross Amount Of Financial Instruments Posted Not Offset in Balance Sheet	0	0
Gross Amounts Of Cash Posted Not Offset In Balance Sheet	0	0
Net Amount Of Liabilities	$ 25,535	$ 4,423