Investments In And Advances To Unconsolidated Real Estate Joint Ventures (Condensed Statements Of Financial Condition For Equity Method Joint Ventures) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Total assets	$ 1,671,337		$ 1,790,971	$ 1,801,761
Total liabilities	1,101,972		1,146,892
Total equity	567,606	$ 600,927	640,070	$ 632,353	$ 640,991	$ 637,608
Total liabilities and equity	1,671,337		1,790,971
Altis At Lakeline - Austin Investors LLC [Member]
Schedule of Equity Method Investments [Line Items]
Cash			628
Restricted cash			5
Other assets			144
Total assets			777
Total equity			777
Total liabilities and equity			777
PGA Design Center Holdings, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Cash	1		1
Investments in joint ventures	3,090		3,090
Total assets	3,091		3,091
Total equity	3,091		3,091
Total liabilities and equity	$ 3,091		$ 3,091