Schedule Of Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Effect of Fourth Quarter Events [Line Items]
Revenue	$ 101	$ 101	$ 98
Operating (expense)	(77)	(72)	(61)
Corporate general and administrative expense	(360)	(396)	(418)
Income (loss) allocable to common shareholders	70	1,916	(2,352)
First Quarter [Member]
Effect of Fourth Quarter Events [Line Items]
Revenue	26	25	24
Operating (expense)	(18)	(18)	(15)
Corporate general and administrative expense	(74)	(104)	(88)
Other income (expense) net	145	60	60
Income (loss) allocable to common shareholders	$ 79	$ (97)	$ 126
Income (loss) per common share – basic	$ 0.01	$ 0.02	$ 0.02
Second Quarter [Member]
Effect of Fourth Quarter Events [Line Items]
Revenue	$ 26	$ 25	$ 24
Operating (expense)	(20)	(18)	(15)
Corporate general and administrative expense	(111)	(127)	(134)
Other income (expense) net	154	60	213
Income (loss) allocable to common shareholders	$ 49	$ (137)	$ (141)
Income (loss) per common share – basic	$ 0.01	$ 0.03	$ 0.03
Third Quarter [Member]
Effect of Fourth Quarter Events [Line Items]
Revenue	$ 25	$ 25	$ 25
Operating (expense)	(34)	(18)	(215)
Corporate general and administrative expense	(53)	(65)	(92)
Other income (expense) net	54	137	106
Income (loss) allocable to common shareholders	$ (8)	$ 2,182	$ (2,320)
Income (loss) per common share – basic	$ 0.01	$ 0.43	$ 0.45
Fourth Quarter [Member]
Effect of Fourth Quarter Events [Line Items]
Revenue	$ 25	$ 26	$ 25
Operating (expense)	(5)	(18)	(16)
Corporate general and administrative expense	(122)	(100)	(104)
Other income (expense) net	53	58	62
Income (loss) allocable to common shareholders	$ (49)	$ (32)	$ (17)
Income (loss) per common share – basic	$ 0.00	$ 0.00	$ 0.00