Related Parties (Schedule Of Related Party Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total	$ 2,480	$ 2,446	$ 2,485
Leasing Agent Fees [Member]
Total	133	32	101
Operation Of Parking Garages [Member]
Total	95	82	184
Building Management Fees [Member]
Total	1,935	1,954	1,832
Property Construction Management Fees [Member]
Total	136	146	147
Dividends Paid On Company Stock Held By Tower [Member]
Total	$ 181	$ 232	$ 221