Note 8 - Stockholders' Equity (Details Textual)							3 Months Ended
	Sep. 04, 2019 USD ($) shares	Aug. 06, 2019 USD ($) $ / shares shares	Aug. 06, 2019 USD ($) $ / shares shares	Aug. 02, 2019 $ / shares shares	Jul. 05, 2019 USD ($) shares	Jun. 06, 2019	Mar. 31, 2020 $ / shares shares	Dec. 31, 2019 $ / shares	Aug. 05, 2019 $ / shares
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares							$ 0.001	$ 0.001
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares							$ 6.36	$ 6.36
Class of Warrant or Right, Issued During Period (in shares)
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio						9
Conversion of Convertible Notes to Units [Member]
Debt Conversion, Original Debt, Amount | $		$ 633,000			$ 52,000
Debt Conversion, Converted Instrument, Shares Issued (in shares)		210,887			521,000
Convertible Promissory Note [Member]
Proceeds from Convertible Debt | $					$ 625,000
Debt Instrument, Interest Rate, Stated Percentage					14.00%
Debt Conversion, Original Debt, Discount of Securities Offered					50.00%
Underwriters [Member]
Proceeds from Issuance or Sale of Equity, Total | $	$ 420,000
Stock Issued During Period, Shares, New Issues (in shares)	75,000
Class of Warrant or Right, Issued During Period (in shares)	250,000
Underwriting Discounts and Commissions | $	$ 32,000
Warrants Issued to Underwriters [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares				$ 6.60
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)				11,958
Public Offering [Member]
Number of Units Offered to Sale (in shares)				1,666,667
Number of Common Stock in Each Unit (in shares)				1
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares				$ 0.001
Number of Common Stock Called by Each Unit (in shares)				1
Unit Offering Price (in dollars per share) | $ / shares				$ 6
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares				$ 6.30
Warrants and Rights Outstanding, Term (Year)				5 years
Underwriters, Additional Common Shares Authorized to Purchase (in shares)				250,000
Underwriters, Additional Warrants Authorized to Purchase (in shares)				250,000
Proceeds from Issuance or Sale of Equity, Total | $			$ 8,840,000
Private Placement Unit [Member]
Number of Common Stock in Each Unit (in shares)		1	1
Number of Common Stock Called by Each Unit (in shares)		1	1
Debt Instrument, Convertible, Conversion Price (in dollars per share) | $ / shares		$ 3	$ 3						$ 8