Distressed Residential Mortgage Loans - Geographic Concentrations of Credit Risk (Details) - Distressed residential mortgage loans held in securitization trusts (net) - Geographic Concentration Risk	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Florida
Concentration Risk [Line Items]
Geographic concentrations	12.60%	12.40%
North Carolina
Concentration Risk [Line Items]
Geographic concentrations	8.10%	8.20%
California
Concentration Risk [Line Items]
Geographic concentrations	7.70%	8.90%
Georgia
Concentration Risk [Line Items]
Geographic concentrations	6.10%	6.90%
Maryland
Concentration Risk [Line Items]
Geographic concentrations	5.40%	3.50%
New York
Concentration Risk [Line Items]
Geographic concentrations	5.20%	5.10%