DERIVATIVE FINANCIAL INSTRUMENTS - Effect on the consolidated statements of operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	$ 103,758	$ (34,915)	$ 281,574	$ 10,557
Eurodollar Future [Member] | Short [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	0	(19)	0	(7)
Treasury Note Future [Member] | Short [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	43,073	(2,191)	122,968	285
Swap [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	39,819	(17,677)	106,103	9,446
Payer Swaption [Member] | Short [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	(34,036)	27,379	(44,944)	1,212
Payer Swaption [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	50,339	(36,360)	91,314	3,710
Interest Rate Floor [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	0	(84)	0	1,300
TBA Contracts [Member] | Short [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	1,013	(5,963)	3,552	3,170
TBA Contracts [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	1,067	0	1,094	(8,559)
Interest Rate Cap
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	$ 2,483	$ 0	$ 1,487	$ 0