v3.19.1
Investment in Loans (Schedule of Commercial Loans: Geographic Distribution) (Details) - Financing Receivables, Unpaid Principal Balance [Member] - Geographic Concentration Risk [Member] - Commercial mortgage loans
3 Months Ended
Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 100.00%
Florida [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 20.10%
Connecticut [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 18.70%
New York [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 12.70%
New Jersey [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 10.40%
North Carolina [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 7.30%
Virginia [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 7.10%
Massachusetts [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 4.90%
Pennsylvania [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 4.30%
Arizona [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 4.00%
Indiana [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 3.80%
Kentucky [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 3.80%
Tennessee [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 1.50%
Louisiana [Member]  
Accounts, Notes, Loans and Financing Receivable [Line Items]  
Percentage of Total Outstanding Unpaid Principal Balance 1.40%