Loans Held for Investment - Key Characteristics of Residential Loan Portfolio (Details) - Seasoned Subprime Residential Mortgage Loans - Loans held for investment, at fair value $ in Thousands	Mar. 31, 2025 USD ($) loan	Dec. 31, 2024 USD ($) loan
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Number of loans | loan	102,392	103,571
Weighted average maturity (years)	20 years 6 months 7 days	20 years 4 months 24 days
Weighted average loan to value	78.70%	78.40%
Weighted average FICO	670	667
Weighted average loan balance (in thousands) | $	$ 110	$ 108
Weighted average percentage owner-occupied	82.50%	85.00%
Weighted average percentage single family residence	77.40%	77.40%
CA
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Weighted average geographic concentration of top five states	15.90%	15.50%
FL
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Weighted average geographic concentration of top five states	8.90%	8.80%
NY
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Weighted average geographic concentration of top five states	8.70%	8.70%
NJ
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Weighted average geographic concentration of top five states	4.30%	4.30%
PA
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
Weighted average geographic concentration of top five states	4.30%	4.30%