VARIABLE INTEREST ENTITIES - FINANCING RECEIVABLES (Additional Information) (Details) RSO (RSO [Member], USD $)	12 Months Ended
	Dec. 31, 2014 Loan	Dec. 31, 2013 Loan	Dec. 31, 2012 Loan	Mar. 31, 2012 Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and receivables	$ 1,935,793,000	$ 1,377,037,000
Number of defaulted loans	2	3
Provision (recovery) for loan loss	1,804,000	3,020,000
Direct financing leases	2,100,000
Middle-market Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and receivables	250,113,000	44,253,000
Provision (recovery) for loan loss	92,000	22,000
Middle-market Loans [Member] | Held for Sale [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and receivables	0	4,473,000
Bank Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and receivables	330,930,000	517,770,000
Provision (recovery) for loan loss	4,173,000	312,000
Bank Loans [Member] | Nonperforming Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and receivables	1,400,000	3,600,000
Number of defaulted loans		1	1	1
Bank Loans [Member] | Held for Sale [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and receivables	282,000	2,377,000
Loans Receivable - Related Party [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision (recovery) for loan loss	$ 1,297,000	$ 0