Loans Receivable and Other Lending Investments, net (Credit Characteristics by Payment Status) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan
Recorded investment in loans, aged by payment status and presented by class
Current	$ 668,769	$ 863,662
Less Than and Equal to 90 Days	0	0
Greater Than 90 Days	37,820	60,725
Total Past Due	37,820	60,725
Loans	$ 706,589	$ 924,387
Financing receivable, number of loans greater than 90 days past due | loan	1	2
Financing receivables, past due time period	10 years 6 months	90 days
Minimum
Recorded investment in loans, aged by payment status and presented by class
Financing receivables, past due time period		4 years
Maximum
Recorded investment in loans, aged by payment status and presented by class
Financing receivables, past due time period		9 years
Senior mortgages
Recorded investment in loans, aged by payment status and presented by class
Current	$ 537,201	$ 703,807
Less Than and Equal to 90 Days	0	0
Greater Than 90 Days	37,820	60,725
Total Past Due	37,820	60,725
Loans	575,021	764,532
Corporate/Partnership loans
Recorded investment in loans, aged by payment status and presented by class
Current	120,658	149,663
Less Than and Equal to 90 Days	0	0
Greater Than 90 Days	0	0
Total Past Due	0	0
Loans	120,658	149,663
Subordinate mortgages
Recorded investment in loans, aged by payment status and presented by class
Current	10,910	10,192
Less Than and Equal to 90 Days	0	0
Greater Than 90 Days	0	0
Total Past Due	0	0
Loans	$ 10,910	$ 10,192