Investment in Loans (Schedule of 90 Days or More Past Due) (Details) - 90 Days or More Past Due [Member] $ in Thousands	Mar. 31, 2019 USD ($)
Commercial mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 days or more past due—accrual status, Unpaid Principal Balance	$ 6,491
90 days or more past due—accrual status, Fair Value	6,491
90 days or more past due—non-accrual status, Unpaid Principal Balance	16,050
90 days or more past due—non-accrual status, , Fair Value	16,050
Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 days or more past due—non-accrual status, Unpaid Principal Balance	18,582
90 days or more past due—non-accrual status, , Fair Value	16,110
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
90 days or more past due—non-accrual status, Unpaid Principal Balance	2,046
90 days or more past due—non-accrual status, , Fair Value	$ 2,025