Income Tax Considerations (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Impairment loss	$ 7,220	$ 13,476
Allowance on other assets	15	117
Interest expense	5,703	9,246
Net operating loss carryforwards	7,428	8,413
Straight-line rentals	916	813
Book-tax basis differential	1,676	4,380
Other	188	348
Total deferred tax assets	23,146	36,793
Valuation allowance	(15,587)	(25,979)
Total deferred tax assets, net of allowance	7,559	10,814
Deferred tax liabilities:
Book-tax basis differential	6,618	10,998
Other	517	553
Total deferred tax liabilities	7,135	$ 11,551
Net operating loss carryforwards	$ 35,400