Note 8 - Preferred Stock and Common Stock Warrants (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended			3 Months Ended		9 Months Ended
	Sep. 15, 2019	May 31, 2019	Sep. 30, 2018	Aug. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Gain (Loss) on Revaluation of Warrants					$ 873	$ 83	$ (965)	$ 83
Common Stock Warrants [Member]
Warrants and Rights Outstanding, Term					3 years		3 years
Exercise of Warrants, Threshold Trading Days							60 days
Exercise of Warrants, Threshold Consecutive Trading Days							90 days
Exercise of Warrants, Conversion Price, Minimum Percentage							175.00%
Series A Convertible Preferred Stock [Member]
Temporary Equity, Stock Issued During Period, Shares, New Issues				50,000
Temporary Equity, Par or Stated Value Per Share				$ 0.0001
Temporary Equity, Issued Price Per Share				$ 1,000
Temporary Equity, Stock Issued During Period, Value, New Issues				$ 50,000
Temporary Equity, Stock Issued During Period, Shares Issued for Services				1,000
Dividends, Preferred Stock, Paid-in-kind	$ 1,700						$ 4,800
Accretion of Discount Amount							2,500
Temporary Equity, Accretion of Dividends					$ 300	$ 300	1,300	$ 300
Series B Convertible Preferred Stock [Member]
Temporary Equity, Stock Issued During Period, Shares, New Issues		20,945	29,055
Temporary Equity, Par or Stated Value Per Share		$ 0.0001
Temporary Equity, Issued Price Per Share		$ 1,000
Temporary Equity, Stock Issued During Period, Value, New Issues		$ 50,000
Temporary Equity, Stock Issued During Period, Shares Issued for Services		999
Dividends, Preferred Stock, Paid-in-kind	$ 1,600						$ 3,000
Convertible Preferred Stock [Member]
Temporary Equity, Issued Price Per Share					$ 1,000		$ 1,000
Temporary Equity, Dividend Rate Percentage							12.00%