Note 10 - Stockholders' Equity (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022	May 19, 2014
Number of Shares Authorized to Issue (in shares)	185,000,000
Common Stock, Shares Authorized (in shares)	175,000,000		175,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.18		$ 0.18
Preferred Stock, Shares Authorized (in shares)	10,000,000		10,000,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001		$ 0.001
Preferred Stock, Shares Issued (in shares)	1,000		1,000
Stockholder Rights Agreement, Number of Preferred Stock Right Distributed for Each Share of Common Stock (in shares)				1
Stockholder Rights Agreement, Acquiring Person, Percentage of Ownership				15.00%
Stockholder Rights Agreement, Acquiring Person, Additional Percentage of Ownership				2.00%
Stockholder Rights Agreement, Initial Exercise Price of Each Right (in dollars per share)				$ 15.00
Stockholder Rights Agreement, Share Price (in dollars per share)				$ 30.00
Consummate a Business Combination, Percentage of Acquired Outstanding Shares	50.00%
Consummate a Business Combination, Percentage of Aggregate Ordinary Voting Power	50.00%
Class of Warrant or Right, Outstanding (in shares)	21,515
Class of Warrant or Right, Exercised During Period (in shares)	0	0
Conversion of Series B Convertible Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted (in shares)	0	0
The 2020 Liability Warrants [Member]
Warrants and Rights Outstanding, Term (Year)	4 years
Warrants Associated with 2020 Offering Consisting of Common Stock and Warrants [Member]
Warrants and Rights Outstanding, Term (Year)	4 years 6 months
The 2020 Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)	1
Warrants Exercisable, Ownership Percentage of Company’s Shares Allowed	4.99%
Common Stock, Convertible, Ownership Percentage of Company’s Shares Allowed	9.99%
Class of Warrant or Right, Outstanding (in shares)	6,490
Series A Junior Participating Preferred Stock [Member]
Preferred Stock, Shares Authorized (in shares)	750,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001
Preferred Stock, Shares Issued (in shares)	0		0
Series A Convertible Preferred Stock [Member]
Preferred Stock, Shares Authorized (in shares)	4,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001
Preferred Stock, Shares Issued (in shares)	0		0
Series B Convertible Preferred Stock [Member]
Preferred Stock, Shares Authorized (in shares)	25,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001
Preferred Stock, Convertible, Conversion Price (in dollars per share)	$ 3.52
Series C Convertible Preferred Stock [Member]
Preferred Stock, Shares Authorized (in shares)	20,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001
Preferred Stock, Shares Issued (in shares)	0		0
Stated Value per Share	$ 1,000
Preferred Stock, Convertible, Ownership Percentage of Company’s Shares Allowed	9.99%