Fair Value - Principal Amount, Carrying Value and Fair Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Financial assets:
Principal Amount	$ 2,361,941			$ 2,515,278
Financial liabilities:
Principal amount, financial liabilities	2,178,885			2,501,221
Current expected credit loss reserve	(126,905)	$ (136,567)	$ (155,365)	(165,932)	$ (155,490)	$ (171,330)	$ (150,214)	$ (76,028)
Commercial mortgage
Financial assets:
Principal Amount	2,361,941			2,515,278
Financial liabilities:
Future funding commitments	105,500			106,300
Securitization bonds payable, net
Financial liabilities:
Principal amount, financial liabilities	982,637			1,094,372
Mortgage and other notes payable, net
Financial liabilities:
Principal amount, financial liabilities	417,577			621,666
Master repurchase facilities
Financial liabilities:
Principal amount, financial liabilities	778,671			785,183
Carrying Value
Financial assets:
Loans and preferred equity held for investment, net	2,363,215			2,518,925
Carrying Value | Securitization bonds payable, net
Financial liabilities:
Financial liabilities	976,998			1,087,074
Carrying Value | Mortgage and other notes payable, net
Financial liabilities:
Financial liabilities	415,182			619,055
Carrying Value | Master repurchase facilities
Financial liabilities:
Financial liabilities	778,671			785,183
Fair Value
Financial assets:
Loans and preferred equity held for investment, net	2,235,035			2,349,346
Fair Value | Securitization bonds payable, net
Financial liabilities:
Financial liabilities	982,637			1,094,372
Fair Value | Mortgage and other notes payable, net
Financial liabilities:
Financial liabilities	395,107			587,349
Fair Value | Master repurchase facilities
Financial liabilities:
Financial liabilities	$ 778,671			$ 785,183