Loans Held-for-Investment, Net of Allowance for Credit Losses - Loans Held-for-Investment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) loan	Dec. 31, 2022 USD ($) loan	Dec. 31, 2021 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance	$ 2,727,179	$ 3,362,006
Unamortized (discount) premium	(19)	(48)
Unamortized net deferred origination fees	(8,674)	(11,808)
Allowance for credit losses	(134,661)	(82,335)	$ (40,897)
Loans held-for-investment, net	2,583,825	3,267,815	$ 3,741,308
Unfunded commitments	$ 160,698	$ 229,607
Number of loans | loan	73	90
Weighted average coupon (as a percent)	8.20%	6.30%
Weighted average years to maturity (in years)	8 months 12 days	1 year
Senior Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance	$ 2,713,672	$ 3,348,242
Unamortized (discount) premium	(19)	(48)
Unamortized net deferred origination fees	(8,674)	(11,808)
Allowance for credit losses	(134,302)	(81,768)
Loans held-for-investment, net	2,570,677	3,254,618
Unfunded commitments	$ 160,698	$ 229,607
Number of loans | loan	72	89
Weighted average coupon (as a percent)	8.20%	6.30%
Weighted average years to maturity (in years)	8 months 12 days	1 year
B-Notes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance	$ 13,507	$ 13,764
Unamortized (discount) premium	0	0
Unamortized net deferred origination fees	0	0
Allowance for credit losses	(359)	(567)
Loans held-for-investment, net	13,148	13,197
Unfunded commitments	$ 0	$ 0
Number of loans | loan	1	1
Weighted average coupon (as a percent)	8.00%	8.00%
Weighted average years to maturity (in years)	3 years 1 month 6 days	4 years 1 month 6 days