Fair Value - Unpaid Principal Balance of Financial Assets and Liabilities, Fair Value Option (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Loans held for investment, subject to HMBS related obligations, Fair Value	$ 19,135,403	$ 18,669,962
Loans held for investment, subject to HMBS related obligations	17,983,144	17,652,495
Loans held for investment, subject to nonrecourse debt, at fair value	10,026,177	9,288,403
Total loans held for investment, subject to nonrecourse debt	9,567,732	9,218,697
Loans held for investment, at fair value	870,081	520,103
Loans held for investment, UBP	790,342	503,949
Loans held for sale, Fair Value	37,461	3,454
Loans held for sale, UBP	34,515	4,331
HMBS related obligations, Fair Value	18,912,226	18,444,370
HMBS related obligations, UBP	17,983,144	17,652,495
Nonrecourse debt, Fair Value	9,736,493	8,954,068
Nonrecourse debt, UPB	9,960,524	9,363,919
Convertible notes, Fair Value	53,800	0
Convertible notes, UPB	$ 40,000	$ 0