INVESTMENTS IN RESIDENTIAL MORTGAGE LOANS - Summary of the Geographic Distribution of the Underlying Residential Mortgage Loans (Details) - Residential Mortgage Loans [Member]	Dec. 31, 2016	Dec. 31, 2015
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	100.00%	100.00%
New York [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	16.70%	14.50%
Florida [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	11.40%	10.70%
California [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	10.30%	12.30%
New Jersey [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	9.60%	13.10%
Maryland [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	4.70%	3.50%
Illinois [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	4.00%	4.30%
Texas [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	3.90%	3.30%
Massachusetts [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	3.50%	3.30%
Pennsylvania [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	2.90%	2.80%
Washington [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	2.80%	3.20%
Other U.S. [Member]
Mortgage Loans on Real Estate [Line Items]
Percentage of Total Outstanding Unpaid Principal Amount	30.20%	29.00%