Convertible Debt at Fair Value (Narrative) (Details) - USD ($)				3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 01, 2017	Feb. 28, 2017	Mar. 16, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Gain (loss) on derivatives and convertible debt				$ 156,000	$ 227,000	$ 603,000	$ 402,000
Series D Preferred Stock [Member]
Debt Instrument [Line Items]
Annual dividend rate						6.25%
Series E Preferred Stock [Member]
Debt Instrument [Line Items]
Annual dividend rate		6.25%				6.25%		6.25%
6.25% Convertible Debt [Member]
Debt Instrument [Line Items]
Interest rate			6.25%	6.25%		6.25%
Principal amount			$ 1,012,000
Number of shares of common stock debt can convert into	97,269		97,269
Maximum ownership percentage of voting stock upon debt conversion			49.00%
Gain (loss) on derivatives and convertible debt				$ (1,000)	$ 25,000	$ 19,000	$ 265,000