Summary Of Significant Accounting Policies (Reconciliation of Cash, Cash Equivalents and Restricted Cash) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Summary Of Significant Accounting Policies [Abstract]
Cash and cash equivalents	$ 117,881	$ 62,786	$ 6,749	$ 37,379
Restricted cash included in Land and building held for development, net	1,088	1,088	1,088	1,088
Cash, cash equivalents and restricted cash at the end of the period	$ 118,969	$ 63,874	$ 7,837	$ 38,467