CURRENT EXPECTED CREDIT LOSSES - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, allowance for credit loss	$ 27,100
Total commitment	$ 2,000,000
Allowance for credit loss, basis points	1.35%
Loans Held for Investment
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, allowance for credit loss	$ 25,454	$ 26,063	$ 0
Unfunded Loan Commitment
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, allowance for credit loss	1,660	$ 2,099	$ 0
Loans Held for Investment
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, allowance for credit loss	25,500
Other Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Interest receivable	$ 9,200