DERIVATIVE INSTRUMENTS - Summary of Purchase and Sale Contracts for TBA Derivatives (Details) - TBA derivatives - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Derivative [Line Items]
Notional	$ 4,174,000	$ 3,117,000
Implied Cost Basis	3,981,439	3,158,058
Implied Market Value	3,991,915	3,136,154
Net Carrying Value	10,476	(21,904)
Purchase contracts
Derivative [Line Items]
Notional	4,389,000	4,237,000
Implied Cost Basis	4,207,018	4,239,001
Implied Market Value	4,217,539	4,209,341
Net Carrying Value	10,521	(29,660)
Sale contracts
Derivative [Line Items]
Notional	(215,000)	(1,120,000)
Implied Cost Basis	(225,579)	(1,080,943)
Implied Market Value	(225,624)	(1,073,187)
Net Carrying Value	$ (45)	$ 7,756