VARIABLE INTEREST ENTITIES - Narrative (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended
		Aug. 31, 2017	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022		Mar. 31, 2020
Variable Interest Entity [Line Items]
Securitized debt of consolidated VIEs			$ 8,805,911		$ 7,744,160	[1]
Mortgage-backed securities	[2]		69,238,185		65,789,907	[1]
Costs incurred in connection with securitization			40,828	$ 45,764
Securitized debt of consolidated VIE, unrealized gain (loss)			(211,900)	298,100
Participations issued			673,431		800,849	[1]
MSR Silo
Variable Interest Entity [Line Items]
Variable interest entity, ownership percentage		100.00%
Consolidated VIEs
Variable Interest Entity [Line Items]
Exposure to obligations of VIEs			1,100,000
Consolidated VIEs | OBX Trust
Variable Interest Entity [Line Items]
Securitized debt of consolidated VIEs			8,800,000		7,700,000
Costs incurred in connection with securitization			1,400	$ 3,400
Contractual principal amount of debt held by third parties			9,900,000		9,000,000
Consolidated VIEs | Consolidation, Eliminations | OBX Trust
Variable Interest Entity [Line Items]
Mortgage-backed securities			1,100,000		1,000,000
VIE, Not Primary Beneficiary | Residential mortgage loans
Variable Interest Entity [Line Items]
Participations issued			$ 673,400		$ 800,800
Multifamily | Consolidated VIEs
Variable Interest Entity [Line Items]
Cut-off date principal balance							$ 500,000
Multifamily | Retained Interest | Consolidated VIEs
Variable Interest Entity [Line Items]
Retained interest notional balance							$ 500,000

[1] (1)Derived from the audited consolidated financial statements at December 31, 2022.

[2] (3)Excludes $1.2 billion and $1.0 billion at March 31, 2023 and December 31, 2022, respectively, of non-Agency mortgage-backed securities in consolidated VIEs pledged as collateral and eliminated from the Company’s Consolidated Statements of Financial Condition.