Concentration of Credit Risk - Schedule of Geographic Composition of Loans Held for Investment Based on Current UPB and Loan Commitment (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Concentration Risk [Line Items]
Loan commitment	$ 5,168,717	$ 4,290,603
Unfunded commitment	$ 236,552	$ 173,595
% of loan commitment	100.00%	100.00%
Total unpaid principal balance	$ 4,934,450	$ 4,118,050
% of loan UPB	100.00%	100.00%
West
Concentration Risk [Line Items]
Loan commitment	$ 1,804,118	$ 1,546,038
Unfunded commitment	$ 107,861	$ 58,655
% of loan commitment	34.90%	36.10%
Total unpaid principal balance	$ 1,697,847	$ 1,488,425
% of loan UPB	34.50%	36.10%
South
Concentration Risk [Line Items]
Loan commitment	$ 1,210,421	$ 860,581
Unfunded commitment	$ 40,673	$ 36,612
% of loan commitment	23.40%	20.00%
Total unpaid principal balance	$ 1,170,443	$ 823,969
% of loan UPB	23.70%	20.10%
East
Concentration Risk [Line Items]
Loan commitment	$ 991,760	$ 1,075,384
Unfunded commitment	$ 46,992	$ 49,037
% of loan commitment	19.20%	25.10%
Total unpaid principal balance	$ 944,768	$ 1,026,347
% of loan UPB	19.10%	24.90%
Various
Concentration Risk [Line Items]
Loan commitment	$ 814,818	$ 573,000
Unfunded commitment	$ 38,664	$ 23,512
% of loan commitment	15.80%	13.30%
Total unpaid principal balance	$ 776,154	$ 549,488
% of loan UPB	15.70%	13.30%
Midwest
Concentration Risk [Line Items]
Loan commitment	$ 347,600	$ 235,600
Unfunded commitment	$ 2,362	$ 5,779
% of loan commitment	6.70%	5.50%
Total unpaid principal balance	$ 345,238	$ 229,821
% of loan UPB	7.00%	5.60%