Loans Held for Investment - Percentage of Securitized Loans Held For Investment Carried at Fair Value by Year Originated (Details) - Loans Held for Investment at Fair Value - Seasoned Subprime Residential Mortgage Loans	Jun. 30, 2023	Dec. 31, 2022
Securitized Loans Held For Investment By Consolidated Variable Interest Entities [Line Items]
2002 and prior	5.50%	6.00%
2003	4.80%	5.00%
2004	9.00%	9.70%
2005	15.30%	16.30%
2006	19.10%	20.30%
2007	20.80%	21.50%
2008	6.50%	6.60%
2009	1.50%	1.50%
2010 and later	17.50%	13.10%
Total	100.00%	100.00%