SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of investments in the VIE (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Securities and other investments owned, at fair value	$ 1,317,101	$ 1,532,095
Loans receivable, at fair value	882,391	873,186
Other assets	14,824	11,525
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Securities and other investments owned, at fair value	30,373	27,445
Loans receivable, at fair value	163,780	205,265
Other assets	8,573	4,956
Maximum exposure to loss	$ 202,726	$ 237,666