FAIR VALUE MEASUREMENTS - Schedule of Securities Valuation Methodology (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2024 USD ($) source
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Number of broker quotation sources | source	2
Government-Backed Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Face Amount	$ 9,561,293
Amortized Cost Basis	9,362,992
Government-Backed Securities | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	9,300,237
Government-Backed Securities | Level 2 | Multiple Quotes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	9,300,237
Government-Backed Securities | Level 2 | Single Quote
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	0
Non-Agency and Other Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Face Amount	9,494,742
Amortized Cost Basis	$ 779,758
Percent of securities	64.20%
Fair Value	$ 520,083
Non-Agency and Other Securities | Minimum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.053
Non-Agency and Other Securities | Minimum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.000
Non-Agency and Other Securities | Minimum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.000
Non-Agency and Other Securities | Minimum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.000
Non-Agency and Other Securities | Maximum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.202
Non-Agency and Other Securities | Maximum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.200
Non-Agency and Other Securities | Maximum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.020
Non-Agency and Other Securities | Maximum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.500
Non-Agency and Other Securities | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.076
Non-Agency and Other Securities | Weighted Average | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.064
Non-Agency and Other Securities | Weighted Average | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.005
Non-Agency and Other Securities | Weighted Average | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Non agency RMBS, measurement input	0.186
Non-Agency and Other Securities | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 809,539
Non-Agency and Other Securities | Level 3 | Multiple Quotes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	548,047
Non-Agency and Other Securities | Level 3 | Single Quote
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	261,492
Mortgage Backed Securities, Excluding Treasury Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Face Amount	19,056,035
Amortized Cost Basis	10,142,750
Fair Value	10,109,776
Mortgage Backed Securities, Excluding Treasury Securities | Multiple Quotes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	9,848,284
Mortgage Backed Securities, Excluding Treasury Securities | Single Quote
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value	$ 261,492