v3.19.1
Investment in Loans (Schedule of Residential Mortgage Loans: Geographic Distribution) (Details) - Financing Receivables, Unpaid Principal Balance [Member] - Residential mortgage loans - Geographic Concentration Risk [Member]
3 Months Ended
Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 100.00%
California [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 48.30%
Florida [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 12.90%
Texas [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 12.70%
Colorado [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 4.40%
Arizona [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 2.80%
Oregon [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 2.40%
Washington [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 2.20%
New York [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 2.20%
Nevada [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 2.10%
Utah [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 1.50%
New Jersey [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 1.30%
Maryland [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 1.10%
Other [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 6.10%