DERIVATIVE FINANCIAL INSTRUMENTS - Effect on the consolidated statements of operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	$ 177,816	$ 45,472
Eurodollar Future [Member] | Short [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	0	12
Treasury Note Future [Member] | Short [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	79,895	2,476
Swap [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	66,284	27,123
Payer Swaption [Member] | Short [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	(10,908)	(26,167)
Payer Swaption [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	40,975	40,070
Interest Rate Floor [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	0	1,384
TBA Contracts [Member] | Short [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	2,539	9,133
TBA Contracts [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	27	(8,559)
Interest Rate Cap
Derivatives, Fair Value [Line Items]
(Losses) gains on derivative instruments	$ (996)	$ 0