Investment in Loans (Schedule of Commercial Loans: Geographic Distribution) (Details) - Geographic Concentration Risk [Member] - Commercial mortgage loans - Financing Receivables, Unpaid Principal Balance [Member]	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2023	Jun. 30, 2022	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	100.00%		100.00%
Florida [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	19.20%		20.50%
NEW YORK
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	14.20%		9.40%
NEW JERSEY
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	0.00%		1.50%
CONNECTICUT
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	2.40%		2.20%
MASSACHUSETTS
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	5.50%		6.20%
MASSACHUSETTS
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	6.30%		5.50%
ARIZONA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	7.70%		9.00%
PENNSYLVANIA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	4.00%		3.70%
ILLINOIS
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	5.00%		4.60%
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance		1.00%	0.40%
OHIO
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	4.10%		3.80%
MICHIGAN
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	6.00%		5.50%
NEW HAMPSHIRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	0.00%		2.20%
Texas [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	14.40%		13.40%
GEORGIA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	4.00%		5.40%
OKLAHOMA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	4.50%		4.20%
RHODE ISLAND
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	0.00%		1.00%
LOUISIANA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total Outstanding Unpaid Principal Balance	1.70%		1.50%