Concentration of Credit Risk - Schedule of Loans Held for Investment Portfolio by Property Type (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%
Multifamily
Concentration Risk [Line Items]
Loan commitment	$ 2,721,250	$ 2,291,490
Unfunded commitment	$ 70,947	$ 73,705
% of loan commitment	52.60%	53.40%
Total unpaid principal balance	$ 2,651,893	$ 2,218,827
% of loan UPB	53.70%	53.90%
Industrial
Concentration Risk [Line Items]
Loan commitment	$ 1,169,955	$ 806,714
Unfunded commitment	$ 92,235	$ 84,381
% of loan commitment	22.60%	18.80%
Total unpaid principal balance	$ 1,077,720	$ 722,333
% of loan UPB	21.80%	17.50%
Office
Concentration Risk [Line Items]
Loan commitment	$ 407,360	$ 454,047
Unfunded commitment	$ 71,143	$ 12,890
% of loan commitment	7.90%	10.60%
Total unpaid principal balance	$ 336,217	$ 441,157
% of loan UPB	6.80%	10.70%
Hotel
Concentration Risk [Line Items]
Loan commitment	$ 390,900	$ 259,100
Unfunded commitment	$ 0	$ 392
% of loan commitment	7.60%	6.00%
Total unpaid principal balance	$ 391,595	$ 258,708
% of loan UPB	7.90%	6.30%
Life Science
Concentration Risk [Line Items]
Loan commitment	$ 333,477	$ 333,477
Unfunded commitment	$ 0	$ 0
% of loan commitment	6.50%	7.80%
Total unpaid principal balance	$ 333,477	$ 333,477
% of loan UPB	6.80%	8.10%
Mixed-Use
Concentration Risk [Line Items]
Loan commitment	$ 78,775	$ 78,775
Unfunded commitment	$ 2,227	$ 2,227
% of loan commitment	1.50%	1.80%
Total unpaid principal balance	$ 76,548	$ 76,548
% of loan UPB	1.60%	1.90%
Self Storage
Concentration Risk [Line Items]
Loan commitment	$ 67,000	$ 67,000
Unfunded commitment	$ 0	$ 0
% of loan commitment	1.30%	1.60%
Total unpaid principal balance	$ 67,000	$ 67,000
% of loan UPB	1.40%	1.60%