Fair Value Measurements - Financial Assets and Liabilities Carried at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Assets:
Non-Agency RMBS, at fair value	$ 1,121,836	$ 1,043,806
Agency MBS, at fair value	1,018,918	102,484
Loans held for investment, at fair value	11,283,775	11,397,046
Derivative assets, at fair value	97	0
Liabilities:
Securitized debt at fair value, collateralized by Loans held for investment	7,314,411	7,601,881
Derivative liabilities, at fair value	0	0
Fair Value, Measurements, Recurring
Assets:
Non-Agency RMBS, at fair value	1,121,836	1,043,806
Agency MBS, at fair value	1,018,918	102,484
Loans held for investment, at fair value	11,283,775	11,397,046
Counterparty and Cash Collateral, netting	(6,890)	(18,817)
Derivative assets, at fair value	97	0
Liabilities:
Secured Financing Agreements, at fair value	338,782	350,238
Securitized debt at fair value, collateralized by Loans held for investment	7,314,411	7,601,881
Counterparty and Cash Collateral, netting	0	0
Derivative liabilities, at fair value	0	0
Fair Value, Measurements, Recurring | Level 1
Assets:
Non-Agency RMBS, at fair value	0	0
Agency MBS, at fair value	0	0
Loans held for investment, at fair value	0	0
Derivatives, at fair value	0	0
Liabilities:
Secured Financing Agreements, at fair value	0	0
Securitized debt at fair value, collateralized by Loans held for investment	0	0
Derivatives, at fair value	0	0
Fair Value, Measurements, Recurring | Level 2
Assets:
Non-Agency RMBS, at fair value	0	0
Agency MBS, at fair value	1,018,918	102,484
Loans held for investment, at fair value	233,229	271,994
Derivatives, at fair value	6,987	18,817
Liabilities:
Secured Financing Agreements, at fair value	338,782	350,238
Securitized debt at fair value, collateralized by Loans held for investment	0	0
Derivatives, at fair value	0	0
Fair Value, Measurements, Recurring | Level 3
Assets:
Non-Agency RMBS, at fair value	1,121,836	1,043,806
Agency MBS, at fair value	0	0
Loans held for investment, at fair value	11,050,546	11,125,052
Derivatives, at fair value	0	0
Liabilities:
Secured Financing Agreements, at fair value	0	0
Securitized debt at fair value, collateralized by Loans held for investment	7,314,411	7,601,881
Derivatives, at fair value	$ 0	$ 0