Fair Value Measurements - Schedule of Financial Instruments Measured at Carrying And Estimated Fair Value (Details) - USD ($)	Sep. 30, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable held-for-investment, net	$ 6,142,749,000	$ 6,877,425,000
Loans receivable held-for-sale	324,188,000	261,709,000
Repurchase agreements	3,451,001,000	3,805,678,000
Term participation facility	385,491,000	465,434,000
Loan participations sold, net	0	120,508,000
Notes payable, net	304,058,000	283,341,000
Secured term loan, net	710,477,000	712,576,000
Debt related to real estate owned, net	279,650,000	289,913,000
Unpaid Principal Balance [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable held-for-investment, net	6,384,893,000	7,044,524,000
Loans receivable held-for-sale	355,971,000	264,065,000
Repurchase agreements	3,451,001,000	3,805,678,000
Term participation facility	385,491,000	465,434,000
Loan participations sold, net		120,634,000
Notes payable, net	306,994,000	286,827,000
Secured term loan, net	719,731,000	725,452,000
Debt related to real estate owned, net	280,000,000	290,000,000
Fair Value [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable held-for-investment, net	6,146,384,000	6,875,377,000
Loans receivable held-for-sale	324,188,000	261,709,000
Repurchase agreements	3,451,001,000	3,805,678,000
Term participation facility	384,589,000	463,010,000
Loan participations sold, net		120,000,000
Notes payable, net	304,115,000	284,904,000
Secured term loan, net	687,343,000	694,620,000
Debt related to real estate owned, net	279,473,000	289,422,000
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable held-for-investment, net	6,146,384,000	6,875,377,000
Loans receivable held-for-sale	324,188,000	261,709,000
Repurchase agreements	3,451,001,000	3,805,678,000
Term participation facility	384,589,000	463,010,000
Loan participations sold, net		120,000,000
Notes payable, net	304,115,000	284,904,000
Secured term loan, net	687,343,000	694,620,000
Debt related to real estate owned, net	$ 279,473,000	$ 289,422,000