DERIVATIVE INSTRUMENTS - Effect of Other Derivative Contracts on the Consolidated Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative [Line Items]
Unrealized Gain (Loss)	$ (188,961)	$ (1,582,495)	$ (1,434,745)	$ (584,109)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives	(92,051)	(394,982)	(514,533)	(211,742)
Futures
Derivative [Line Items]
Realized Gain (Loss)	5,100	35,500
Unrealized Gain (Loss)	5,800	1,800
Gain on derivative			5,700	35,500
Purchase commitments
Derivative [Line Items]
Realized Gain (Loss)	0	0	0	0
Unrealized Gain (Loss)	(5,266)	9,124	7,173	4,870
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives	(5,266)	9,124	7,173	4,870
US Treasury Futures, Options
Derivative [Line Items]
Gain on derivative			9,000
Loss on derivative				(6,800)
Net TBA derivatives
Derivative [Line Items]
Realized Gain (Loss)	163,432	40,561	91,391	15,694
Unrealized Gain (Loss)	(86,855)	(18,181)	32,381	12,649
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives	76,577	22,380	123,772	28,343
Net interest rate swaptions
Derivative [Line Items]
Realized Gain (Loss)		(21,180)	(9,230)	(33,511)
Unrealized Gain (Loss)		(113,792)	0	(59,304)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives		(134,972)	(9,230)	(92,815)
Futures contracts | Futures
Derivative [Line Items]
Realized Gain (Loss)	(383,194)	(362,660)	(314,896)	(323,113)
Unrealized Gain (Loss)	219,832	71,146	(321,352)	170,973
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives	$ (163,362)	$ (291,514)	$ (636,248)	$ (152,140)