LOANS HELD-FOR-INVESTMENT (Allowance for Financing Receivable) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2020	Jun. 30, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses as of beginning of the period	$ 19,779,000	$ 0	$ 0
Provision for credit losses	7,905,000	17,777,000	25,682,000	$ 0
Allowance for credit losses end of period	27,684,000	19,779,000	27,684,000
Cumulative Effect, Period Of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses as of beginning of the period		2,002,000	2,002,000
Mezzanine loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses as of beginning of the period	14,541,000	0	0
Provision for credit losses	6,728,000	13,047,000
Allowance for credit losses end of period	21,269,000	14,541,000	21,269,000
Mezzanine loans | Cumulative Effect, Period Of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses as of beginning of the period		1,494,000	1,494,000
Senior loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses as of beginning of the period	809,000	0	0
Provision for credit losses	(317,000)	341,000
Allowance for credit losses end of period	492,000	809,000	492,000
Senior loans | Cumulative Effect, Period Of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses as of beginning of the period		468,000	468,000
Broadly syndicated loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses as of beginning of the period	4,429,000	0	0
Provision for credit losses	1,494,000	4,389,000
Allowance for credit losses end of period	$ 5,923,000	4,429,000	5,923,000
Broadly syndicated loans | Cumulative Effect, Period Of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses as of beginning of the period		$ 40,000	$ 40,000