VARIABLE INTEREST ENTITIES - LOANS HELD FOR INVESTMENT (Weighted Average Life of Middle-Market Loans, at Amortized Cost) (Details) RSO (Middle-market Loans [Member], RSO [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized Cost	$ 250,113	$ 44,253
B Notes [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less than one year	0	0
Mezzanine Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Greater than one year and less than five years	132,353	13,027
Whole Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Five years or greater	$ 117,760	$ 31,226