VARIABLE INTEREST ENTITIES - Narrative (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
		Aug. 31, 2017	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Variable Interest Entity [Line Items]
Securitized debt of consolidated VIEs			$ 7,744,160	$ 5,155,633
Estimated fair value	[1]		65,789,907	63,655,674
Costs incurred in connection with securitization			162,729	186,014	$ 222,195
Unrealized gains (losses) on debt held by third parties			1,200,000	(69,400)
Participations issued			800,849	1,049,066
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			1,000,000
Consolidated VIEs | Multifamily
Variable Interest Entity [Line Items]
Cut-off date principal balance						$ 500,000
Derecognized securities			424,000
Derecognized securitization vehicles			391,900
Net gains (losses) on disposal of investments and other			33,400
Consolidated VIEs | Multifamily | Retained Interest
Variable Interest Entity [Line Items]
Retained interest notional balance						$ 500,000
Consolidated VIEs | OBX Trust
Variable Interest Entity [Line Items]
Securitized debt of consolidated VIEs			7,700,000	4,600,000
Costs incurred in connection with securitization			7,600	5,600
Contractual principal amount of debt held by third parties			9,000,000	4,600,000
Consolidated VIEs | OBX Trust | Consolidation, Eliminations
Variable Interest Entity [Line Items]
Estimated fair value			1,000,000	780,800
VIE, Not Primary Beneficiary | Residential mortgage loans
Variable Interest Entity [Line Items]
Participations issued			$ 800,000	$ 1,000,000

[1] (2) Excludes $0.0 million and $44.2 million at December 31, 2022 and 2021, respectively, of agency mortgage-backed securities, $1.0 billion and $350.4 million at December 31, 2022 and 2021, respectively, of non-Agency mortgage-backed securities in consolidated VIEs pledged as collateral and eliminated from the Company’s Consolidated Statements of Financial Condition.