VARIABLE INTEREST ENTITIES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Variable Interest Entity [Line Items]
Securitized debt of consolidated VIEs	$ 26,601,790		$ 26,601,790		$ 19,540,678	[1]
Securitized debt of consolidated VIE, unrealized gain (loss)	(92,900)	$ (430,400)	(322,900)	$ (339,600)
Net gains (losses) on investments and other	561,927	1,723,713	1,456,242	160,841
Costs incurred in connection with securitization	50,340	43,921	148,422	127,382
Outstanding participating interests	1,831,657		1,831,657		1,154,816	[1]
OBX 2025-NQM8
Variable Interest Entity [Line Items]
Net gains (losses) on investments and other	400
Consolidated VIEs
Variable Interest Entity [Line Items]
Exposure to obligations of VIEs	3,000,000		3,000,000
Securitized debt of consolidated VIEs	26,300,000		26,300,000		19,500,000
Contractual principal amount of debt held by third parties	26,800,000		26,800,000		20,500,000
Costs incurred in connection with securitization	8,100	$ 5,000	20,600	$ 14,000
Consolidated VIEs | Consolidation, Eliminations
Variable Interest Entity [Line Items]
Non-Agency mortgage-backed securities	3,000,000		3,000,000		2,300,000
VIE, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Outstanding participating interests	$ 1,800,000		$ 1,800,000		$ 1,200,000

[1] (1)Derived from the audited consolidated financial statements at December 31, 2024.