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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Derivative [Line Items]
Unrealized Gain (Loss)	$ (1,582,495)	$ 1,475,547	$ (584,109)	$ 1,360,977
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives	(394,982)	240,790	(211,742)	216,605
Futures
Derivative [Line Items]
Realized Gain (Loss)	(362,660)	309,397	(323,113)	185,716
Unrealized Gain (Loss)	71,146	131,578	170,973	229,940
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives	(291,514)	440,975	(152,140)	415,656
Futures | Secured Overnight Financing Rate (SOFR)
Derivative [Line Items]
Realized Gain (Loss)		(18,900)	(6,800)	(18,900)
Unrealized Gain (Loss)			(5,600)	13,200
Purchase commitments
Derivative [Line Items]
Realized Gain (Loss)	0	0	0	0
Unrealized Gain (Loss)	9,124	2,457	4,870	(122)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives	9,124	2,457	4,870	(122)
Net TBA derivatives
Derivative [Line Items]
Realized Gain (Loss)	40,561	(81,964)	15,694	(136,452)
Unrealized Gain (Loss)	(18,181)	(41,777)	12,649	12,710
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives	22,380	(123,741)	28,343	(123,742)
Net interest rate swaptions
Derivative [Line Items]
Realized Gain (Loss)	(21,180)	(27,860)	(33,511)	(25,538)
Unrealized Gain (Loss)	(113,792)	(51,041)	(59,304)	(43,627)
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives	$ (134,972)	$ (78,901)	$ (92,815)	(69,165)
Credit derivatives
Derivative [Line Items]
Realized Gain (Loss)				(19,282)
Unrealized Gain (Loss)				13,260
Amount of Gain/(Loss) Recognized in Net Gains (Losses) on Other Derivatives				$ (6,022)