Note 9 - Stockholders' Equity (Details Textual) - $ / shares						1 Months Ended	15 Months Ended
	Feb. 11, 2021	Sep. 23, 2020	Nov. 11, 2019	Jun. 21, 2017	Dec. 21, 2016	Jun. 30, 2016	Mar. 31, 2021	Dec. 31, 2019
Class of Warrant or Right, Issued During Period (in shares)							150,418
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)							$ 3.58	$ 3.73
Warrants Issued in June 2016 [Member]
Class of Warrant or Right, Issued During Period (in shares)						2,000
Class of Warrant or Right, Grants in Period, Grant Date Fair Value (in dollars per share)						$ 5.40
Class of Warrants or Rights, Vesting Period (Year)						1 year
Class of Warrants or Rights, Vested During the Period (in shares)				1,000	1,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)							$ 10.50
Warrant In Connection With Amended Subordinated Loan [Member]
Class of Warrant or Right, Issued During Period (in shares)			1
Class of Warrant or Right, Grants in Period, Grant Date Fair Value (in dollars per share)			$ 2.40
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)			$ 3
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)			41,667
Warrants and Rights Outstanding, Term (Year)			5 years
Warrant Issued in Connection with Amended 2017 Credit Agreement [Member]
Class of Warrant or Right, Issued During Period (in shares)		1
Class of Warrant or Right, Grants in Period, Grant Date Fair Value (in dollars per share)		$ 1.42
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 3.75
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)		1,000,000
Class of Warrant or Right, Period Following Issuance at which Warrants are Exercisable (Year)		1 year
Warrants and Rights Outstanding, Term (Year)		5 years
Warrants Issued in Connection With the Conversion of Subordinated Loan Agreement to Common Stock [Member]
Class of Warrant or Right, Issued During Period (in shares)	1
Class of Warrant or Right, Grants in Period, Grant Date Fair Value (in dollars per share)	$ 2.02
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 2.507
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)	150,418
Class of Warrant or Right, Period Following Issuance at which Warrants are Exercisable (Year)	1 year
Warrants and Rights Outstanding, Term (Year)	5 years