DERIVATIVE INSTRUMENTS - Effect of Other Derivative Contracts on the Consolidated Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Unrealized Gain (Loss)	$ 3,480,708	$ 2,198,486	$ (904,532)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives and Financial Instruments	$ 1,278,732	120,574
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net gains (losses) on derivatives
Futures
Derivative [Line Items]
Realized Gain (Loss)	$ 3,825,072	683,534
Unrealized Gain (Loss)	141,366	(101,199)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives and Financial Instruments	3,966,438	582,335
Purchase commitments
Derivative [Line Items]
Realized Gain (Loss)	0	0
Unrealized Gain (Loss)	460	860
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives and Financial Instruments	460	860
TBA derivatives
Derivative [Line Items]
Realized Gain (Loss)	(2,729,866)	(354,410)
Unrealized Gain (Loss)	(100,990)	(47,332)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives and Financial Instruments	(2,830,856)	(401,742)
Interest rate swaptions
Derivative [Line Items]
Realized Gain (Loss)	(43,124)	(78,431)
Unrealized Gain (Loss)	195,084	2,387
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives and Financial Instruments	151,960	(76,044)
Credit derivatives
Derivative [Line Items]
Realized Gain (Loss)	3,657	8,234
Unrealized Gain (Loss)	(12,927)	6,931
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives and Financial Instruments	$ (9,270)	$ 15,165