Note 2 - Liquidity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended
	Jan. 22, 2018	Jan. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Common Stock, Par or Stated Value Per Share	$ 0.001		$ 0.001	$ 0.001
Conversion From Series A Preferred Stock to Common Stock [Member]
Conversion of Stock, Shares Issued	1,400,462	1,400,462
Warrants Issued in Connection with the January 2018 Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	1,000,000	1,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 12	$ 12
Class of Warrant or Right, Term	5 years
Warrants Issued in Connection with the January 2018 Offering [Member] | Maximum [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 15
Additional Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights		12
Underwriter Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 15	$ 15
Class of Warrant or Right, Term	5 years	5 years
Underwriter Warrants [Member] | Maximum [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	50,000	50,000
January 2018 Offering [Member]
Stock Issued During Period, Shares, New Issues	1,000,000	1,000,000
Share Price	$ 12
Proceeds from Issuance or Sale of Equity, Total	$ 10,800	$ 10,800
January 2018 Offering [Member] | Additional Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	131,375