INVESTMENTS IN RESIDENTIAL MORTGAGE LOANS - Schedule of Residential Mortgage Loans Outstanding by Loan Type, Excluding REO and Linked Transactions (Footnote) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Feb. 27, 2013
Mortgage Loans on Real Estate [Line Items]
Threshold period, loans past due	30 days
Net unamortized discounts and premiums	$ 15.2
Residential Mortgage Loan [Member]
Mortgage Loans on Real Estate [Line Items]
Residential mortgage loans, federal income tax basis	1,159.1	33.9
Reverse Mortgage Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Interest in reverse mortgage loans	70.00%		70.00%
Total unpaid principal balance	0.3	0.2
Percentage of loans that have reached a termination event	77.00%	82.00%
Maximum [Member] | Performing Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Threshold period, loans past due	30 days
Greater than 60 Days Past Due [Member]
Mortgage Loans on Real Estate [Line Items]
Number of investments on non-accrual status	$ 2.3