Income Tax Considerations (Schedule Of Income Tax Provision) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal statutory income tax rate, percent	35.00%	35.00%	35.00%
Net (loss) income before taxes of taxable REIT subsidiary	$ (5,788)	$ 20,295	$ (989)
Federal (benefit) provision at statutory rate of 35%	(2,026)	7,103	(346)
Valuation allowance decrease	0	(1,251)	(309)
Effect of change in statutory rate on net deferrals	282	0	0
Other	176	(54)	6
Federal income tax provision (benefit) of taxable REIT subsidiary (1)	(1,568)	5,798	(649)
Texas franchise tax	1,551	1,058	701
Total	$ (17)	$ 6,856	$ 52