Multi-family Loans, at Fair Value - Preferred Equity and Mezzanine Loan Investments (Details) - Variable Interest Entity, Not Primary Beneficiary - Preferred equity and mezzanine loan investments - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Investment amount	$ 118,307	$ 163,392
Deferred loan fees, net	(672)	(1,169)
Unrealized gains, net	2,386	1,370
Total, at Fair Value	$ 120,021	$ 163,593