Mortgage And Other Notes Receivable (Schedule of Financing Receivables, Allowance for Credit Loss Roll Forward) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	$ 1,600
Financing Receivable, Allowance for Credit Loss, Ending Balance	5,500
Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Ending Balance	$ 3,900