Fair Value Measurements - Schedule of Financial Instruments Measured at Carrying And Estimated Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable held-for-investment, net	$ 7,029,856	$ 6,340,295
Interests in loans receivable held-for- investment, net		161,850
Repurchase agreements	3,918,703	3,489,511
Loan participations sold, net	273,487	167,744
Notes payable, net	98,107	48,000
Secured term loan, net	738,180	739,762
Debt related to real estate owned, net	289,852	289,806
Unpaid Principal Balance [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable held-for-investment, net	7,139,571	6,441,238
Interests in loans receivable held-for- investment, net		161,566
Repurchase agreements	3,918,703	3,489,511
Loan participations sold, net	274,252	168,322
Notes payable, net	100,512	48,000
Secured term loan, net	758,904	762,717
Debt related to real estate owned, net	290,000	290,000
Fair Value [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable held-for-investment, net	7,043,862	6,434,157
Interests in loans receivable held-for- investment, net		161,883
Repurchase agreements	3,918,703	3,484,834
Loan participations sold, net	273,856	168,738
Notes payable, net	100,275	48,000
Secured term loan, net	724,753	762,717
Debt related to real estate owned, net	280,473	281,723
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable held-for-investment, net	7,043,862	6,434,157
Interests in loans receivable held-for- investment, net		161,883
Repurchase agreements	3,918,703	3,484,834
Loan participations sold, net	273,856	168,738
Notes payable, net	100,275	48,000
Secured term loan, net	724,753	762,717
Debt related to real estate owned, net	$ 280,473	$ 281,723