SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of investments in the VIE (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Securities and other investments owned, at fair value	$ 1,197,587	$ 1,129,268
Other assets	45,034	45,116
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Securities and other investments owned, at fair value	35,190	33,743
Loans receivable, at fair value	52,856	46,700
Other assets	2,655	3,755
Maximum exposure to loss	$ 90,701	$ 84,198