FAIR VALUE MEASUREMENTS - Real Estate And Other Securities Valuation Methodology and Results (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2025 USD ($) source	Dec. 31, 2024 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Face Amount	$ 17,078,481	$ 15,878,274
Amortized Cost Basis	8,563,776	7,259,894
Government and government-backed securities	$ 8,657,974	7,245,667
Number of broker quotation sources | source	2
Multiple Quotes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	$ 8,593,451	7,196,838
Single Quote
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	64,523	48,829
Agency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Face Amount	7,895,808	6,672,189
Amortized Cost Basis	7,708,001	6,510,235
Agency | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	7,751,904	6,450,643
Agency | Level 2 | Multiple Quotes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	7,751,904	6,450,643
Agency | Level 2 | Single Quote
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	0	0
Collateral
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Face Amount	268,896	243,355
Amortized Cost Basis	260,448	234,397
Collateral | Fair Value, Inputs, Level 2 and 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	266,612	242,227
Collateral | Fair Value, Inputs, Level 2 and 3 | Multiple Quotes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	227,934	217,049
Collateral | Fair Value, Inputs, Level 2 and 3 | Single Quote
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	38,678	25,178
Non-Agency Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Face Amount	8,913,777	8,962,730
Amortized Cost Basis	$ 595,327	$ 515,262
Percent of securities	76.90%	82.10%
Fair Value	$ 491,437	$ 453,978
Non-Agency Securities | Minimum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.050	0.047
Non-Agency Securities | Minimum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.000	0.000
Non-Agency Securities | Minimum | CDR
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.000	0.000
Non-Agency Securities | Minimum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.000	0.000
Non-Agency Securities | Maximum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.200	0.200
Non-Agency Securities | Maximum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.250	0.200
Non-Agency Securities | Maximum | CDR
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.019	0.019
Non-Agency Securities | Maximum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.500	0.500
Non-Agency Securities | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.073	0.069
Non-Agency Securities | Weighted Average | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.060	0.063
Non-Agency Securities | Weighted Average | CDR
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.004	0.005
Non-Agency Securities | Weighted Average | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Discount Rate	0.168	0.170
Non-Agency Securities | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	$ 639,458	$ 552,797
Non-Agency Securities | Level 3 | Multiple Quotes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	613,613	529,146
Non-Agency Securities | Level 3 | Single Quote
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Government and government-backed securities	$ 25,845	$ 23,651
Residential Mortgage Loans HFS, at Fair Value | Minimum | Discount Rate | Non-performing loans | Financial Asset Acquired and No Credit Deterioration [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.092	0.085
Residential Mortgage Loans HFS, at Fair Value | Minimum | CDR | Non-performing loans | Financial Asset Acquired and No Credit Deterioration [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.105	0.013
Residential Mortgage Loans HFS, at Fair Value | Maximum | Discount Rate | Non-performing loans | Financial Asset Acquired and No Credit Deterioration [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.095	0.093
Residential Mortgage Loans HFS, at Fair Value | Maximum | CDR | Non-performing loans | Financial Asset Acquired and No Credit Deterioration [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.177	0.051
Residential Mortgage Loans HFS, at Fair Value | Weighted Average | Discount Rate | Non-performing loans | Financial Asset Acquired and No Credit Deterioration [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.094	0.088
Residential Mortgage Loans HFS, at Fair Value | Weighted Average | CDR | Non-performing loans | Financial Asset Acquired and No Credit Deterioration [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.152	0.038