Quarterly Operating Results (Schedule Of Quarterly Operations) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Operating Results [Abstract]
Revenue	$ 8,309	$ 8,841	$ 4,811	$ 13,227	$ 14,306	$ 14,666	$ 16,177	$ 15,903	$ 35,188	$ 61,052	$ 65,057
Operating expenses	5,353	11,644	8,960	13,862	13,412	14,386	14,562	13,825	39,819	56,185	56,905
Operating income (loss)	2,956	(2,803)	(4,149)	(635)	894	280	1,615	2,078	(4,631)	4,867	8,152
Net gain (loss) on dispositions of assets	(5)	(3)	(1)	(9)	(45)	(14)	(16)	39	(18)	(36)	5,570
Equity in earnings (loss) of joint venture				80	(405)	(84)	166	513	80	190	(218)
Net gain (loss) on derivatives and convertible debt	(5,722)	131	19	(759)	(155)	(223)	(456)	(237)	(6,331)	(1,071)	317
Other income (expense), net	25	(4)	(58)	(28)	(24)	(27)	(24)	(29)	(65)	(104)	(83)
Interest expense	(2,328)	(2,103)	(2,070)	(1,980)	(1,807)	(1,912)	(2,094)	(2,163)	(8,481)	(7,976)	(8,326)
Earnings (loss) before income taxes	(5,074)	(4,782)	(6,259)	(3,331)	(1,542)	(1,980)	(809)	201	(19,446)	(4,130)	5,505
Income tax benefit (expense)	35	(27)	61	306	(282)	(8)	(461)	(186)	375	(937)	(335)
Net earnings (loss)	(5,039)	(4,809)	(6,198)	(3,025)	(1,824)	(1,988)	(1,270)	15	(19,071)	(5,067)	5,170
Loss attributable to noncontrolling interest	2	2	2	1	2	10	6	1	7	19	195
Net earnings (loss) attributable to controlling interests	(5,037)	(4,807)	(6,196)	(3,024)	(1,822)	(1,978)	(1,264)	16	(19,064)	(5,048)	5,365
Dividends declared and undeclared on preferred stock	(159)	(169)	(144)	(145)	(144)	(145)	(144)	(145)	(617)	(578)	(578)
Net earnings (loss) attributable to common shareholders	$ (5,196)	$ (4,976)	$ (6,340)	$ (3,169)	$ (1,966)	$ (2,123)	$ (1,408)	$ (129)	$ (19,681)	$ (5,626)	$ 4,787
Earnings (loss) per Share
Total - Basic Earnings (Loss) per Share	$ (0.38)	$ (0.42)	$ (0.53)	$ (0.27)	$ (0.17)	$ (0.18)	$ (0.12)	$ (0.01)	$ (1.59)	$ (0.48)	$ 0.40
Total - Diluted Earnings (Loss) per Share	$ (0.38)	$ (0.42)	$ (0.53)	$ (0.27)	$ (0.17)	$ (0.18)	$ (0.12)	$ (0.01)	$ (1.59)	$ (0.48)	$ 0.40