Concentration of Credit Risk - Summary of Geographic Composition of Loans Held for Investment Based on Current UPB and Loan Commitment (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Loans And Leases Receivable Disclosure [Line Items]
Loan commitment	$ 4,869,045	$ 5,429,146
Unfunded commitment	$ 300,502	$ 426,061
% of loan commitment	100.00%	100.00%
Total unpaid principal balance	$ 4,567,250	$ 5,004,798
% of loan UPB	100.00%	100.00%
East
Loans And Leases Receivable Disclosure [Line Items]
Loan commitment	$ 1,700,456	$ 1,844,087
Unfunded commitment	$ 58,500	$ 73,104
% of loan commitment	34.90%	33.90%
Total unpaid principal balance	$ 1,643,128	$ 1,772,155
% of loan UPB	36.00%	35.40%
West
Loans And Leases Receivable Disclosure [Line Items]
Loan commitment	$ 1,589,171	$ 1,629,727
Unfunded commitment	$ 137,194	$ 179,104
% of loan commitment	32.60%	30.00%
Total unpaid principal balance	$ 1,449,512	$ 1,450,623
% of loan UPB	31.70%	29.00%
South
Loans And Leases Receivable Disclosure [Line Items]
Loan commitment	$ 1,210,468	$ 1,496,382
Unfunded commitment	$ 87,487	$ 138,836
% of loan commitment	24.90%	27.60%
Total unpaid principal balance	$ 1,122,981	$ 1,358,087
% of loan UPB	24.60%	27.10%
Midwest
Loans And Leases Receivable Disclosure [Line Items]
Loan commitment	$ 229,950	$ 319,950
Unfunded commitment	$ 10,516	$ 17,130
% of loan commitment	4.70%	5.90%
Total unpaid principal balance	$ 219,434	$ 302,820
% of loan UPB	4.80%	6.10%
Various
Loans And Leases Receivable Disclosure [Line Items]
Loan commitment	$ 139,000	$ 139,000
Unfunded commitment	$ 6,805	$ 17,887
% of loan commitment	2.90%	2.60%
Total unpaid principal balance	$ 132,195	$ 121,113
% of loan UPB	2.90%	2.40%