Repurchase Agreements, Loan Participations Sold, Net, Notes Payable, Net, Secured Term Loan, Net and Debt Related to Real Estate Owned, Net - Summary of Interest Expense and Amortization (Details) - USD ($) $ in Thousands	3 Months Ended		8 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Securities Loaned And Securities Sold Under Agreement To Repurchase Gross Including Not Subject To Master Netting Arrangement [Abstract]
Interest on secured financings	$ 28,400	$ 31,403		$ 86,989	$ 101,230
Interest on secured term loan	11,749	3,928		34,954	13,640
Interest expense	2,619		$ 13,000	12,968
Amortization of financing costs	5,302	4,409		16,277	14,211
Total interest and related expense	$ 48,070	$ 39,740		$ 151,188	$ 129,081