DERIVATIVE INSTRUMENTS - Effect of Other Derivative Contracts on the Consolidated Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Derivative [Line Items]
Unrealized Gain (Loss)	$ 900,902	$ (956,272)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Derivatives	167,330	(184,367)
Futures
Derivative [Line Items]
Realized Gain (Loss)	(8,680)	118,332
Unrealized Gain (Loss)	145,709	(314,878)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Derivatives	137,029	(196,546)
Futures | Secured Overnight Financing Rate (SOFR)
Derivative [Line Items]
Realized Gain (Loss)	0
Unrealized Gain (Loss)	1,200
Purchase commitments
Derivative [Line Items]
Realized Gain (Loss)	0	0
Unrealized Gain (Loss)	(6,613)	865
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Derivatives	(6,613)	865
Net TBA derivatives
Derivative [Line Items]
Realized Gain (Loss)	(8,615)	(153,849)
Unrealized Gain (Loss)	14,898	215,360
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Derivatives	6,283	61,511
Net interest rate swaptions
Derivative [Line Items]
Realized Gain (Loss)	0	2,323
Unrealized Gain (Loss)	30,631	(45,999)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Derivatives	$ 30,631	(43,676)
Credit derivatives
Derivative [Line Items]
Realized Gain (Loss)		(1,312)
Unrealized Gain (Loss)		(5,209)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Derivatives		$ (6,521)