CONSOLIDATED VARIABLE INTEREST ENTITIES (Details) - CLO - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Total assets	$ 886,146	$ 884,637
Total liabilities	691,887	690,755
Net equity in VIEs (eliminated in consolidation)	194,260	193,882
Total equity	194,260	193,882
Total liabilities and equity	886,147	884,637
Mortgage loan receivables held for investment, net, at amortized cost
Variable Interest Entity [Line Items]
Total assets	881,719	880,385
Accrued interest receivable
Variable Interest Entity [Line Items]
Total assets	4,427	4,252
Senior and unsecured debt obligations
Variable Interest Entity [Line Items]
Total liabilities	690,507	689,961
Accrued expenses
Variable Interest Entity [Line Items]
Total liabilities	$ 1,379	$ 794