Note 10 - Stockholders' Equity (Details Textual) - USD ($)					6 Months Ended
	Feb. 11, 2021	Sep. 23, 2020	Aug. 13, 2020	Nov. 11, 2019	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)					$ 3.57		$ 3.73
Fair Value Adjustment of Warrants					$ 304,000	$ 0
Class of Warrant or Right, Issued During Period (in shares)					150,418
Warrant Issued in connection with Conversion of Subordinated Debt [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)	150,418
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 2.507
Class of Warrant or Right, Grant Date Fair Value (in dollars per share)	$ 2.02
Class of Warrant or Right, Period Following Issuance at which Warrants are Exercisable (Year)	1 year
Fair Value Adjustment of Warrants	$ 304,000
Warrant In Connection With Amended Subordinated Loan [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)				41,667
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)				$ 3.00
Class of Warrant or Right, Issued During Period (in shares)				1
Warrants and Rights Outstanding, Term (Year)				5 years
Class of Warrant or Right, Grants in Period, Grant Date Fair Value (in dollars per share)				$ 2.40
Warrant Issued in Connection with Amended 2017 Credit Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)		1,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 3.75
Class of Warrant or Right, Period Following Issuance at which Warrants are Exercisable (Year)		1 year
Class of Warrant or Right, Issued During Period (in shares)		1
Warrants and Rights Outstanding, Term (Year)		5 years
Class of Warrant or Right, Grants in Period, Grant Date Fair Value (in dollars per share)		$ 1.42
Warrants Issued in Connection With the Conversion of Subordinated Loan Agreement to Common Stock [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)	150,418
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 2.507
Class of Warrant or Right, Period Following Issuance at which Warrants are Exercisable (Year)	1 year
Class of Warrant or Right, Issued During Period (in shares)	1
Warrants and Rights Outstanding, Term (Year)	5 years
Class of Warrant or Right, Grants in Period, Grant Date Fair Value (in dollars per share)	$ 2.02
Subordinated Debt [Member]
Gain (Loss) on Extinguishment of Debt, Total			$ 552,000
Conversion from Subordinated Promissory Note to Common Stock [Member]
Debt Conversion, Original Debt, Percentage of Total Debt	50.00%		50.00%
Debt Conversion, Original Debt, Amount	$ 1,250,000		$ 1,250,000
Debt Conversion, Accrued Interest, Amount	$ 62,000		$ 265,000
Debt Conversion, Converted Instrument, Shares Issued (in shares)	601,674		403,602
Debt Conversion, Converted Instrument, Amount			$ 963,000